1
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Wong EL, Folpini G, Zhou Y, Albaqami MD, Petrozza A. Electron Spectroscopy and Microscopy: A Window into the Surface Electronic Properties of Polycrystalline Metal Halide Perovskites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2310240. [PMID: 38708696 DOI: 10.1002/adma.202310240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 03/04/2024] [Indexed: 05/07/2024]
Abstract
In the past years, an increasing number of experimental techniques have emerged to address the need to unveil the chemical, structural, and electronic properties of perovskite thin films with high vertical and lateral spatial resolutions. One of these is angle-resolved photoemission electron spectroscopy which can provide direct access to the electronic band structure of perovskites, with the aim of overcoming elusive and controversial information due to the complex data interpretation of purely optical spectroscopic techniques. This perspective looks at the information that can be gleaned from the direct measurement of the electronic band structure of single crystal perovskites and the challenges that remain to be overcame to extend this technique to heterogeneous polycrystalline metal halide perovskites.
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Affiliation(s)
- E Laine Wong
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Raffaele Rubattino, 81, Milano, 20134, Italy
| | - Giulia Folpini
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Raffaele Rubattino, 81, Milano, 20134, Italy
| | - Yang Zhou
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Raffaele Rubattino, 81, Milano, 20134, Italy
| | - Minirah Dukhi Albaqami
- Chemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Annamaria Petrozza
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Raffaele Rubattino, 81, Milano, 20134, Italy
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2
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Cheng F, Wang P, Xu C, Liao Q, Zhang S, Sun H, Fan W, Liu G, Li Z, Kong Y, Wang L, Li F, Kang Z, Zhang Y. The dynamic surface evolution of halide perovskites induced by external energy stimulation. Natl Sci Rev 2024; 11:nwae042. [PMID: 38487497 PMCID: PMC10939416 DOI: 10.1093/nsr/nwae042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 01/05/2024] [Accepted: 01/29/2024] [Indexed: 03/17/2024] Open
Abstract
Tracking the dynamic surface evolution of metal halide perovskite is crucial for understanding the corresponding fundamental principles of photoelectric properties and intrinsic instability. However, due to the volatility elements and soft lattice nature of perovskites, several important dynamic behaviors remain unclear. Here, an ultra-high vacuum (UHV) interconnection system integrated by surface-sensitive probing techniques has been developed to investigate the freshly cleaved surface of CH3NH3PbBr3 in situ under given energy stimulation. On this basis, the detailed three-step chemical decomposition pathway of perovskites has been clarified. Meanwhile, the evolution of crystal structure from cubic phase to tetragonal phase on the perovskite surface has been revealed under energy stimulation. Accompanied by chemical composition and crystal structure evolution, electronic structure changes including energy level position, hole effective mass, and Rashba splitting have also been accurately determined. These findings provide a clear perspective on the physical origin of optoelectronic properties and the decomposition mechanism of perovskites.
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Affiliation(s)
- Feiyu Cheng
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Pengdong Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Chenzhe Xu
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qingliang Liao
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Suicai Zhang
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Haochun Sun
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Wenqiang Fan
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Guodong Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhiyun Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Yaping Kong
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Li Wang
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Fangsen Li
- Vacuum Interconnected Nanotech Workstation (Nano-X), Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
| | - Zhuo Kang
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yue Zhang
- Academy for Advanced Interdisciplinary Science and Technology, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
- Beijing Key Laboratory for Advanced Energy Materials and Technologies, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips, Ministry of Education, Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
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3
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Park J, Huh S, Choi YW, Kang D, Kim M, Kim D, Park S, Choi HJ, Kim C, Yi Y. Visualizing the Low-Energy Electronic Structure of Prototypical Hybrid Halide Perovskite through Clear Band Measurements. ACS NANO 2024; 18:7570-7579. [PMID: 38377437 DOI: 10.1021/acsnano.3c12587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Organic-inorganic hybrid perovskites (OIHPs) are a promising class of materials that rival conventional semiconductors in various optoelectronic applications. However, unraveling the precise nature of their low-energy electronic structures continues to pose a significant challenge, primarily due to the absence of clear band measurements. Here, we investigate the low-energy electronic structure of CH3NH3PbI3 (MAPI3) using angle-resolved photoelectron spectroscopy combined with ab initio density functional theory. We successfully visualize the electronic structure of MAPI3 near the bulk valence band maximum by using a laboratory photon source (He Iα, 21.2 eV) at low temperature and explore its fundamental properties. The observed valence band exhibits a highly isotropic and parabolic band characterized by small effective masses of 0.20-0.21 me, without notable spectral signatures associated with a large polaron or the Rashba effect, subjects that are intensely debated in the literature. Concurrently, our spin-resolved measurements directly disprove the giant Rashba scenario previously suggested in a similar perovskite compound by establishing an upper limit for the Rashba parameter (αR) of 0.28 eV Å. Our results unveil the unusually complex nature of the low-energy electronic structure of OIHPs, thereby advancing our fundamental understanding of this important class of materials.
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Affiliation(s)
- Jeehong Park
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Soonsang Huh
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Young Woo Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Donghee Kang
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Minsoo Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Donghan Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Soohyung Park
- Advanced Analysis Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Hyoung Joon Choi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron System, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Yeonjin Yi
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
- Van der Waals Materials Research Center, Yonsei University, Seoul 03722, Republic of Korea
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4
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Lei Y, Liu W, Li C, Da S, Zheng Y, Wu Y, Ran F. Microstress for metal halide perovskite solar cells: from source to influence and management. NANOSCALE 2024; 16:2765-2788. [PMID: 38258472 DOI: 10.1039/d3nr05264h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The power conversion efficiency of metal halide perovskite solar cells (PSCs) has increased dramatically in recent years, but there are still major bottlenecks in the commercial application of such materials, including intrinsic instability caused by external stimuli such as water, oxygen, and radiation, as well as local stress generated inside the perovskite and external stress caused by poor interlayer contact. However, some crucial sources of instability cannot be overcome by conventional encapsulation engineering. Among them, the tensile strain can weaken the chemical bonds in the perovskite lattice, thereby reducing the defects formation energy and activation energy of ion migration and accelerating the degradation rate of the perovskite crystal. This review expounds the latest in-depth understanding of microstrain in perovskite film from the thermodynamic sources and influences on the perovskite physicochemical structure and photoelectric performance. Furthermore, it also summarizes the effective strategies for strain regulation and interlayer contact performance improvement, which are conducive to the improvement of photovoltaic performance and internal stability of PSCs. Finally, we present a prospective outlook on how to achieve more stable and higher efficiency PSCs through strain engineering.
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Affiliation(s)
- Yixiao Lei
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Wenwu Liu
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Caixia Li
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Shiji Da
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Yawen Zheng
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Youzhi Wu
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
| | - Fen Ran
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China.
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5
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Zhao B, Li Y, Chen X, Han Y, Wei S, Wu K, Zhang X. Engineering Carrier Dynamics in Halide Perovskites by Dynamical Lattice Distortion. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300386. [PMID: 37807821 PMCID: PMC10667814 DOI: 10.1002/advs.202300386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 08/31/2023] [Indexed: 10/10/2023]
Abstract
The electronic structure of halide perovskites is central to their carrier dynamics, enabling the excellent optoelectronic performance. However, the experimentally resolved transient absorption spectra exhibit large discrepancies from the commonly computed electronic structure by density functional theory. Using pseudocubic CsPbI3 as a prototype example, here, it is unveiled with both ab initio molecular dynamics simulations and transmission electron microscopy that there exists pronounced dynamical lattice distortion in the form of disordered instantaneous octahedral tilting. Rigorous first-principles calculations reveal that the lattice distortion substantially alters the electronic band structure through renormalizing the band dispersions and the interband transition energies. Most notably, the electron and hole effective masses increase by 65% and 88%, respectively; the transition energy between the two highest valence bands decreases by about one half, agreeing remarkably well with supercontinuum transient-absorption measurements. This study further demonstrates how the resulting electronic structure modulates various aspects of the carrier dynamics such as carrier transport, hot-carrier relaxation, Auger recombination, and carrier multiplication in halide perovskites. The insights provide a pathway to engineer carrier transport and relaxation via lattice distortion, enabling the promise to achieve ultrahigh-efficiency photovoltaic devices.
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Affiliation(s)
- Bai‐Qing Zhao
- Beijing Computational Science Research CenterBeijing100193China
| | - Yulu Li
- State Key Laboratory of Molecular Reaction DynamicsDalian Institute of Chemical PhysicsChinese Academy of SciencesDalianLiaoning116023China
| | - Xuan‐Yan Chen
- Beijing Computational Science Research CenterBeijing100193China
| | - Yaoyao Han
- State Key Laboratory of Molecular Reaction DynamicsDalian Institute of Chemical PhysicsChinese Academy of SciencesDalianLiaoning116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Su‐Huai Wei
- Beijing Computational Science Research CenterBeijing100193China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction DynamicsDalian Institute of Chemical PhysicsChinese Academy of SciencesDalianLiaoning116023China
- University of Chinese Academy of SciencesBeijing100049China
| | - Xie Zhang
- Beijing Computational Science Research CenterBeijing100193China
- School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an710072China
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6
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Iqbal Z, Zu F, Musiienko A, Gutierrez-Partida E, Köbler H, Gries TW, Sannino GV, Canil L, Koch N, Stolterfoht M, Neher D, Pavone M, Muñoz-García AB, Abate A, Wang Q. Interface Modification for Energy Level Alignment and Charge Extraction in CsPbI 3 Perovskite Solar Cells. ACS ENERGY LETTERS 2023; 8:4304-4314. [PMID: 37854052 PMCID: PMC10580311 DOI: 10.1021/acsenergylett.3c01522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 09/20/2023] [Indexed: 10/20/2023]
Abstract
In perovskite solar cells (PSCs) energy level alignment and charge extraction at the interfaces are the essential factors directly affecting the device performance. In this work, we present a modified interface between all-inorganic CsPbI3 perovskite and its hole-selective contact (spiro-OMeTAD), realized by the dipole molecule trioctylphosphine oxide (TOPO), to align the energy levels. On a passivated perovskite film, with n-octylammonium iodide (OAI), we created an upward surface band-bending at the interface by TOPO treatment. This improved interface by the dipole molecule induces a better energy level alignment and enhances the charge extraction of holes from the perovskite layer to the hole transport material. Consequently, a Voc of 1.2 V and a high-power conversion efficiency (PCE) of over 19% were achieved for inorganic CsPbI3 perovskite solar cells. Further, to demonstrate the effect of the TOPO dipole molecule, we present a layer-by-layer charge extraction study by a transient surface photovoltage (trSPV) technique accomplished by a charge transport simulation.
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Affiliation(s)
- Zafar Iqbal
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Fengshuo Zu
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Artem Musiienko
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Emilio Gutierrez-Partida
- Institute
for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
| | - Hans Köbler
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Thomas W. Gries
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Gennaro V. Sannino
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Department
of Physics “Ettore Pancini”, University of Naples Federico II, Comp. Univ. Monte S. Angelo, via Cintia 26, 80126 Naples, Italy
| | - Laura Canil
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Norbert Koch
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Institut
für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Martin Stolterfoht
- Institute
for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
- The
Chinese University of Hong Kong, Electronic
Engineering Department, Shatin N.T., Hong Kong 999077, People’s
Republic of China
| | - Dieter Neher
- Institute
for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany
| | - Michele Pavone
- Department
of Chemical Sciences, University of Naples
Federico II, Comp. Univ.
Monte S. Angelo, Via Cintia 26, 80126 Naples, Italy
| | - Ana Belen Muñoz-García
- Department
of Physics “Ettore Pancini”, University of Naples Federico II, Comp. Univ. Monte S. Angelo, via Cintia 26, 80126 Naples, Italy
| | - Antonio Abate
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Department
of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
- Department
of Chemical Materials and Production Engineering, University of Naples Federico II, Piazzale Vincenzo Tecchio 80, 80125 Naples, Italy
| | - Qiong Wang
- Helmholtz-Zentrum
Berlin für Materialien und Energie GmbH. Hahn-Meitner-Platz 1, 14109 Berlin, Germany
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7
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Yang LS, Lin EC, Hua YH, Hsu CA, Chiu HZ, Lo PH, Chao YC. Circularly Polarized Photoluminescence of Chiral 2D Halide Perovskites at Room Temperature. ACS APPLIED MATERIALS & INTERFACES 2022; 14:54090-54100. [PMID: 36420750 DOI: 10.1021/acsami.2c16359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Chiral halide perovskites have attracted considerable attention because of their chiroptical, second-harmonic generation, and ferroelectricity properties and their potential application in chiroptoelectronics and chiral spintronics. However, the fundamental research of these properties is insufficient. In this work, chiral perovskites were synthesized using precursor solutions with various stoichiometric ratios ⟨n⟩. The chiral perovskite film prepared from the solution with ⟨n⟩ = 1 is composed of (R-/S-/rac-MBA)2PbBr4, whereas the films prepared from the solutions with ⟨n⟩ larger than 1 are a mixture of (R-/S-/rac-MBA)2(CsMA)n-1PbnBr3n+1 with n = 1 and large n values. A photoluminescence quantum yield of approximately 90 was obtained. Symmetric circular dichroism (CD) spectra were observed without an external magnetic field. Under various magnetic fields, magnetic field-induced CD features are superimposed with the intrinsic chirality-induced CD features. For the ⟨n⟩ = 1 chiral perovskite film, the energy level splitting induced by chiral molecules are a few 10 μeV, whereas the energy level splitting induced by magnetic fields are at the range of ∼-250 to ∼250 μeV. Circularly polarized photoluminescence spectra were observed at room temperature and associated with the spin-preserved energy funneling from highly energetic phases to the lower energetic phases.
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Affiliation(s)
- Lan-Sheng Yang
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - En-Chi Lin
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - Yi-Hsiu Hua
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - Chin-An Hsu
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - Hao-Zhe Chiu
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - Pei-Hsuan Lo
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
| | - Yu-Chiang Chao
- Department of Physics, National Taiwan Normal University, Taipei11677, Taiwan, R.O.C
- Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu300093, Taiwan
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8
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Bao C, Gao F. Physics of defects in metal halide perovskites. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 85:096501. [PMID: 35763940 DOI: 10.1088/1361-6633/ac7c7a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Metal halide perovskites are widely used in optoelectronic devices, including solar cells, photodetectors, and light-emitting diodes. Defects in this class of low-temperature solution-processed semiconductors play significant roles in the optoelectronic properties and performance of devices based on these semiconductors. Investigating the defect properties provides not only insight into the origin of the outstanding performance of perovskite optoelectronic devices but also guidance for further improvement of performance. Defects in perovskites have been intensely studied. Here, we review the progress in defect-related physics and techniques for perovskites. We survey the theoretical and computational results of the origin and properties of defects in perovskites. The underlying mechanisms, functions, advantages, and limitations of trap state characterization techniques are discussed. We introduce the effect of defects on the performance of perovskite optoelectronic devices, followed by a discussion of the mechanism of defect treatment. Finally, we summarize and present key challenges and opportunities of defects and their role in the further development of perovskite optoelectronic devices.
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Affiliation(s)
- Chunxiong Bao
- Department of Physics, Chemistry, and Biology, Linköping University, Sweden
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, People's Republic of China
| | - Feng Gao
- Department of Physics, Chemistry, and Biology, Linköping University, Sweden
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9
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Naujoks T, Jayabalan R, Kirsch C, Zu F, Mandal M, Wahl J, Waibel M, Opitz A, Koch N, Andrienko D, Scheele M, Brütting W. Quantum Efficiency Enhancement of Lead-Halide Perovskite Nanocrystal LEDs by Organic Lithium Salt Treatment. ACS APPLIED MATERIALS & INTERFACES 2022; 14:28985-28996. [PMID: 35695840 DOI: 10.1021/acsami.2c04018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Surface-defect passivation is key to achieving a high photoluminescence quantum yield in lead halide perovskite nanocrystals. However, in perovskite light-emitting diodes, these surface ligands also have to enable balanced charge injection into the nanocrystals to yield high efficiency and operational lifetime. In this respect, alkaline halides have been reported to passivate surface trap states and increase the overall stability of perovskite light emitters. On the one side, the incorporation of alkaline ions into the lead halide perovskite crystal structure is considered to counterbalance cation vacancies, whereas on the other side, the excess halides are believed to stabilize the colloids. Here, we report an organic lithium salt, viz. LiTFSI, as a halide-free surface passivation on perovskite nanocrystals. We show that treatment with LiTFSI has multiple beneficial effects on lead halide perovskite nanocrystals and LEDs derived from them. We obtain a higher photoluminescence quantum yield and a longer exciton lifetime and a radiation pattern that is more favorable for light outcoupling. The ligand-induced dipoles on the nanocrystal surface shift their energy levels toward a lower hole-injection barrier. Overall, these effects add up to a 4- to 7-fold boost of the external quantum efficiency in proof-of-concept LED structures, depending on the color of the used lead halide perovskite nanocrystal emitters.
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Affiliation(s)
- Tassilo Naujoks
- Institut für Physik, Universität Augsburg, Augsburg 86135, Germany
| | | | - Christopher Kirsch
- Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Tübingen 72076, Germany
| | - Fengshuo Zu
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin 12489, Germany
| | - Mukunda Mandal
- Max Planck Institute für Polymerforschung, Ackermannweg 10, Mainz 55128, Germany
| | - Jan Wahl
- Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Tübingen 72076, Germany
| | - Martin Waibel
- Institut für Physik, Universität Augsburg, Augsburg 86135, Germany
| | - Andreas Opitz
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin 12489, Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin 12489, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin 12489, Germany
| | - Denis Andrienko
- Max Planck Institute für Polymerforschung, Ackermannweg 10, Mainz 55128, Germany
| | - Marcus Scheele
- Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Tübingen 72076, Germany
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10
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Kirstein E, Yakovlev DR, Glazov MM, Zhukov EA, Kudlacik D, Kalitukha IV, Sapega VF, Dimitriev GS, Semina MA, Nestoklon MO, Ivchenko EL, Kopteva NE, Dirin DN, Nazarenko O, Kovalenko MV, Baumann A, Höcker J, Dyakonov V, Bayer M. The Landé factors of electrons and holes in lead halide perovskites: universal dependence on the band gap. Nat Commun 2022; 13:3062. [PMID: 35654813 PMCID: PMC9163162 DOI: 10.1038/s41467-022-30701-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
The Landé or g-factors of charge carriers are decisive for the spin-dependent phenomena in solids and provide also information about the underlying electronic band structure. We present a comprehensive set of experimental data for values and anisotropies of the electron and hole Landé factors in hybrid organic-inorganic (MAPbI3, MAPb(Br0.5Cl0.5)3, MAPb(Br0.05Cl0.95)3, FAPbBr3, FA0.9Cs0.1PbI2.8Br0.2, MA=methylammonium and FA=formamidinium) and all-inorganic (CsPbBr3) lead halide perovskites, determined by pump-probe Kerr rotation and spin-flip Raman scattering in magnetic fields up to 10 T at cryogenic temperatures. Further, we use first-principles density functional theory (DFT) calculations in combination with tight-binding and k ⋅ p approaches to calculate microscopically the Landé factors. The results demonstrate their universal dependence on the band gap energy across the different perovskite material classes, which can be summarized in a universal semi-phenomenological expression, in good agreement with experiment. The Landé factors govern all the spin-related basic phenomena and are the key parameters which guide spintronics applications. Here, Kirstein et al. demonstrate a universal dependence of the Landé factors on the bandgap energy of several perovskite materials.
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Affiliation(s)
- E Kirstein
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany.
| | - D R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany. .,Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia.
| | - M M Glazov
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - E A Zhukov
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany.,Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - D Kudlacik
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany
| | - I V Kalitukha
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - V F Sapega
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - G S Dimitriev
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - M A Semina
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - M O Nestoklon
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - E L Ivchenko
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - N E Kopteva
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany
| | - D N Dirin
- Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | - O Nazarenko
- Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | - M V Kovalenko
- Department of Chemistry and Applied Biosciences, Laboratory of Inorganic Chemistry, ETH Zürich, 8093, Zürich, Switzerland.,Department of Advanced Materials and Surfaces, Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
| | - A Baumann
- Experimental Physics VI, Julius-Maximilian University of Würzburg, 97074, Würzburg, Germany
| | - J Höcker
- Experimental Physics VI, Julius-Maximilian University of Würzburg, 97074, Würzburg, Germany
| | - V Dyakonov
- Experimental Physics VI, Julius-Maximilian University of Würzburg, 97074, Würzburg, Germany
| | - M Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44227, Dortmund, Germany.,Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
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11
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García-Fernández A, Svanström S, Sterling CM, Gangan A, Erbing A, Kamal C, Sloboda T, Kammlander B, Man GJ, Rensmo H, Odelius M, Cappel UB. Experimental and Theoretical Core Level and Valence Band Analysis of Clean Perovskite Single Crystal Surfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106450. [PMID: 35122466 DOI: 10.1002/smll.202106450] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Indexed: 06/14/2023]
Abstract
A detailed understanding of the surface and interface properties of lead halide perovskites is of interest for several applications, in which these materials may be used. To develop this understanding, the study of clean crystalline surfaces can be an important stepping stone. In this work, the surface properties and electronic structure of two different perovskite single crystal compositions (MAPbI3 and Csx FA1- x PbI3 ) are investigated using synchrotron-based soft X-ray photoelectron spectroscopy (PES), molecular dynamics simulations, and density functional theory. The use of synchrotron-based soft X-ray PES enables high surface sensitivity and nondestructive depth-profiling. Core level and valence band spectra of the single crystals are presented. The authors find two carbon 1s contributions at the surface of MAPbI3 and assign these to MA+ ions in an MAI-terminated surface and to MA+ ions below the surface. It is estimated that the surface is predominantly MAI-terminated but up to 30% of the surface can be PbI2 -terminated. The results presented here can serve as reference spectra for photoelectron spectroscopy investigations of technologically relevant polycrystalline thin films, and the findings can be utilized to further optimize the design of device interfaces.
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Affiliation(s)
- Alberto García-Fernández
- Division of Applied Physical Chemistry, Department of Chemistry, KTH - Royal Institute of Technology, Stockholm, SE-100 44, Sweden
| | - Sebastian Svanström
- Condensed Matter Physics of Energy Materials, Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, SE-751 20, Sweden
| | - Cody M Sterling
- Department of Physics, Stockholm University, AlbaNova University Center, Stockholm, 10691, Sweden
| | - Abhijeet Gangan
- Department of Physics, Stockholm University, AlbaNova University Center, Stockholm, 10691, Sweden
| | - Axel Erbing
- Department of Physics, Stockholm University, AlbaNova University Center, Stockholm, 10691, Sweden
| | - Chinnathambi Kamal
- Department of Physics, Stockholm University, AlbaNova University Center, Stockholm, 10691, Sweden
- Theory and Simulations Laboratory, HRDS, Raja Ramanna Centre for Advanced Technology, Indore, Madhya Pradesh, 452013, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, Maharashtra, 400094, India
| | - Tamara Sloboda
- Division of Applied Physical Chemistry, Department of Chemistry, KTH - Royal Institute of Technology, Stockholm, SE-100 44, Sweden
| | - Birgit Kammlander
- Division of Applied Physical Chemistry, Department of Chemistry, KTH - Royal Institute of Technology, Stockholm, SE-100 44, Sweden
| | - Gabriel J Man
- Condensed Matter Physics of Energy Materials, Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, SE-751 20, Sweden
| | - Håkan Rensmo
- Condensed Matter Physics of Energy Materials, Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, SE-751 20, Sweden
| | - Michael Odelius
- Department of Physics, Stockholm University, AlbaNova University Center, Stockholm, 10691, Sweden
| | - Ute B Cappel
- Division of Applied Physical Chemistry, Department of Chemistry, KTH - Royal Institute of Technology, Stockholm, SE-100 44, Sweden
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12
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Zhang W, Ono LK, Xue J, Qi Y. Atomic Level Insights into Metal Halide Perovskite Materials by Scanning Tunneling Microscopy and Spectroscopy. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202112352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Wei Zhang
- Energy Materials and Surface Sciences Unit (EMSSU) Okinawa Institute of Science and Technology Graduate University (OIST) 1919-1 Tancha, Onna-son Kunigami-gun Okinawa 904-0495 Japan
| | - Luis K. Ono
- Energy Materials and Surface Sciences Unit (EMSSU) Okinawa Institute of Science and Technology Graduate University (OIST) 1919-1 Tancha, Onna-son Kunigami-gun Okinawa 904-0495 Japan
| | - Jiamin Xue
- School of Physical Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Yabing Qi
- Energy Materials and Surface Sciences Unit (EMSSU) Okinawa Institute of Science and Technology Graduate University (OIST) 1919-1 Tancha, Onna-son Kunigami-gun Okinawa 904-0495 Japan
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13
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Zu F, Shin D, Koch N. Electronic properties of metal halide perovskites and their interfaces: the basics. MATERIALS HORIZONS 2022; 9:17-24. [PMID: 34816849 DOI: 10.1039/d1mh01106e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We have witnessed tremendous progress of metal halide perovskite (MHP)-based optoelectronic devices, especially in the field of photovoltaics. Despite intensive research in the past few years, questions still remain regarding their fundamental optoelectronic properties, among which the electronic properties exhibit an interplay of numerous phenomena that deserve serious scrutiny. In this Focus article, we aim to provide a contemporary understanding of the unique electronic properties that has been resolved by the community. First introducing some of the basic concepts established in semiconductor physics, the intrinsic and extrinsic electronic properties of the MHPs are disentangled and explained. With this, the complex interplay of interface-, dopant-, and surface state-induced electronic states in determining the electrostatic landscape in the material can be comprehended, and the energy level alignment in device architectures more reliably assessed.
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Affiliation(s)
- Fengshuo Zu
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
| | - Dongguen Shin
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
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14
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Zu F, Warby JH, Stolterfoht M, Li J, Shin D, Unger E, Koch N. Photoinduced Energy-Level Realignment at Interfaces between Organic Semiconductors and Metal-Halide Perovskites. PHYSICAL REVIEW LETTERS 2021; 127:246401. [PMID: 34951794 DOI: 10.1103/physrevlett.127.246401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/19/2021] [Accepted: 11/02/2021] [Indexed: 06/14/2023]
Abstract
In contrast to the common conception that the interfacial energy-level alignment is affixed once the interface is formed, we demonstrate that heterojunctions between organic semiconductors and metal-halide perovskites exhibit huge energy-level realignment during photoexcitation. Importantly, the photoinduced level shifts occur in the organic component, including the first molecular layer in direct contact with the perovskite. This is caused by charge-carrier accumulation within the organic semiconductor under illumination and the weak electronic coupling between the junction components.
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Affiliation(s)
- Fengshuo Zu
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Jonathan H Warby
- Institut für Physik und Astronomie, Universität Potsdam, 14776 Potsdam, Germany
| | - Martin Stolterfoht
- Institut für Physik und Astronomie, Universität Potsdam, 14776 Potsdam, Germany
| | - Jinzhao Li
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
| | - Dongguen Shin
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Eva Unger
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489 Berlin, Germany
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15
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Zhang W, Ono LK, Xue J, Qi Y. Atomic Level Insights into Metal Halide Perovskite Materials by Scanning Tunneling Microscopy and Spectroscopy. Angew Chem Int Ed Engl 2021; 61:e202112352. [PMID: 34647403 DOI: 10.1002/anie.202112352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Indexed: 11/07/2022]
Abstract
Metal halide perovskite materials (MHPMs) have attracted significant attention because of their superior optoelectronic properties and versatile applications. The power conversion efficiency of MHPM solar cells (PSCs) has skyrocketed to 25.5 %. Although the performance of PSCs is already competitive, several important challenges still need to be solved to realize commercial applications. A thorough understanding of surface atomic structures and structure-property relationships is at the heart of these remaining issues. Scanning tunneling microscopy (STM) and spectroscopy (STS) can be used to characterize the surface properties of MHPMs, which can offer crucial insights into MHPMs at the atomic scale. This Review summarizes recent progress in STM and STS studies on MHPMs, with a focus on the surface properties. We provide understanding from the comparative perspective of several different MHPMs. We also highlight a series of novel phenomena observed by STM and STS. Finally, we outline a few research topics of primary importance for future studies.
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Affiliation(s)
- Wei Zhang
- Energy Materials and Surface Sciences Unit (EMSSU), Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Luis K Ono
- Energy Materials and Surface Sciences Unit (EMSSU), Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yabing Qi
- Energy Materials and Surface Sciences Unit (EMSSU), Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
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16
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Menzel D, Tejada A, Al-Ashouri A, Levine I, Guerra JA, Rech B, Albrecht S, Korte L. Revisiting the Determination of the Valence Band Maximum and Defect Formation in Halide Perovskites for Solar Cells: Insights from Highly Sensitive Near-UV Photoemission Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:43540-43553. [PMID: 34472345 DOI: 10.1021/acsami.1c10171] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Using advanced near-UV photoemission spectroscopy (PES) in constant final state mode (CFSYS) with a very high dynamic range, we investigate the triple-cation lead halide perovskite Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3 and gain detailed insights into the density of occupied states (DOS) in the valence band and band gap. A valence band model is established which includes the parabolic valence band edge and an exponentially decaying band tail in a single equation. This allows us to precisely determine two valence band maxima (VBM) at different k-vectors in the angle-integrated spectra, where the highest one, resulting from the VBM at the R-point in the Brillouin zone, is found between -1.50 to -1.37 eV relative to the Fermi energy EF. We investigate quantitatively the formation of defect states in the band gap up to EF upon decomposition of the perovskites during sample transfer, storage, and measurements: during near-UV-based PES, the density of defect states saturates at a value that is around 4 orders of magnitude below the density of states at the valence band edge. However, even short air exposure, or 3 h of X-ray illumination, increased their density by almost a factor of six and ∼40, respectively. Upon prolonged storage in vacuum, the formation of a distinct defect peak is observed. Thus, near-UV CFSYS with modeling as shown here is demonstrated as a powerful tool to characterize the valence band and quantify defect states in lead halide perovskites.
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Affiliation(s)
- Dorothee Menzel
- Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
| | - Alvaro Tejada
- Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
- Departamento de Ciencias, Sección Física, Pontificia Universidad Católica del Perú, Av. Universitaria 1801, 15088 Lima, Peru
| | - Amran Al-Ashouri
- Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
| | - Igal Levine
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
| | - Jorge Andres Guerra
- Departamento de Ciencias, Sección Física, Pontificia Universidad Católica del Perú, Av. Universitaria 1801, 15088 Lima, Peru
| | - Bernd Rech
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Scientific Management, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
- Faculty IV-Electrical Engineering and Computer Science, Technical University Berlin, Marchstraße 23, 10587 Berlin, Germany
| | - Steve Albrecht
- Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
- Faculty IV-Electrical Engineering and Computer Science, Technical University Berlin, Marchstraße 23, 10587 Berlin, Germany
| | - Lars Korte
- Young Investigator Group Perovskite Tandem Solar Cells, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Kekuléstraße 5, 12489 Berlin, Germany
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17
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Octavio de Araujo L, Sabino FP, Rêgo CRC, Guedes-Sobrinho D. Bulk Rashba Effect Splitting and Suppression in Polymorphs of Metal Iodine Perovskites. J Phys Chem Lett 2021; 12:7245-7251. [PMID: 34313438 DOI: 10.1021/acs.jpclett.1c02048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We quantified the bulk Rashba splitting and suppression in polymorphs of MA(Pb, Sn, Ge, or Si)I3 perovskites. The low-computational-cost DFT-1/2 quasiparticle correction was performed for all structures, combined with the inclusion of spin-orbit coupling (SOC) effects. The presence of SOC and symmetry breaking from the metal off-centering octahedral distortion are indispensable and essential conditions for Rashba splitting, whose magnitude emerges from the Pb → Si sequence. Additionally, the quasiparticle correction provides energy bandgaps for MAPbI3 (cubic, tetragonal, and orthorhombic), MASnI3 (cubic and tetragonal), and MAGeI3 (cubic) that are in outstanding agreement with experimental results. However, while gap energies are yielded collaboratively from the metal off-centering and relative octahedral tiltings, the bulk Rashba suppression is reached for metal on-centering (octahedral platonic-like) configurations that are thermodynamically stable even when the charge polarization is kept invariant among metal-I bonds in the polymorphs.
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Affiliation(s)
- Luis Octavio de Araujo
- Chemistry Department, Federal University of Paraná, Curitiba, CEP 81531-980 Paraná, Brazil
| | | | - Celso R C Rêgo
- Institute of Nanotechnology Hermann von Helmholtz Platz, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
| | - Diego Guedes-Sobrinho
- Chemistry Department, Federal University of Paraná, Curitiba, CEP 81531-980 Paraná, Brazil
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18
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Multimodal host-guest complexation for efficient and stable perovskite photovoltaics. Nat Commun 2021; 12:3383. [PMID: 34099667 PMCID: PMC8185086 DOI: 10.1038/s41467-021-23566-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/29/2021] [Indexed: 11/13/2022] Open
Abstract
Formamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host–guest complexation strategy to overcome this challenge using a crown ether, dibenzo-21-crown-7, which acts as a vehicle that assembles at the interface and delivers Cs+ ions into the interior while modulating the material. This provides a local gradient of doping at the nanoscale that assists in photoinduced charge separation while passivating surface and bulk defects, stabilizing the perovskite phase through a synergistic effect of the host, guest, and host–guest complex. The resulting solar cells show power conversion efficiencies exceeding 24% and enhanced operational stability, maintaining over 95% of their performance without encapsulation for 500 h under continuous operation. Moreover, the host contributes to binding lead ions, reducing their environmental impact. This supramolecular strategy illustrates the broad implications of host–guest chemistry in photovoltaics. It remains a challenge to achieve a balance between performance and stability, as well as addressing the environmental impact of perovskite solar cells. Here, the authors propose a multimodal host-guest complexation strategy enabling these shortcomings to be addressed simultaneously.
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19
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Shin D, Zu F, Cohen AV, Yi Y, Kronik L, Koch N. Mechanism and Timescales of Reversible p-Doping of Methylammonium Lead Triiodide by Oxygen. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100211. [PMID: 33938045 DOI: 10.1002/adma.202100211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 03/05/2021] [Indexed: 06/12/2023]
Abstract
Understanding and controlling the energy level alignment at interfaces with metal halide perovskites (MHPs) is essential for realizing the full potential of these materials for use in optoelectronic devices. To date, however, the basic electronic properties of MHPs are still under debate. Particularly, reported Fermi level positions in the energy gap vary from indicating strong n- to strong p-type character for nominally identical materials, raising serious questions about intrinsic and extrinsic defects as dopants. In this work, photoemission experiments demonstrate that thin films of the prototypical methylammonium lead triiodide (MAPbI3 ) behave like an intrinsic semiconductor in the absence of oxygen. Oxygen is then shown to be able to reversibly diffuse into and out of the MAPbI3 bulk, requiring rather long saturation timescales of ≈1 h (in: ambient air) and over 10 h (out: ultrahigh vacuum), for few 100 nm thick films. Oxygen in the bulk leads to pronounced p-doping, positioning the Fermi level universally ≈0.55 eV above the valence band maximum. The key doping mechanism is suggested to be molecular oxygen substitution of iodine vacancies, supported by density functional theory calculations. This insight rationalizes previous and future electronic property studies of MHPs and calls for meticulous oxygen exposure protocols.
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Affiliation(s)
- Dongguen Shin
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - Fengshuo Zu
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
| | - Ayala V Cohen
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth, 76100, Israel
| | - Yeonjin Yi
- Institute of Physics and Applied Physics & Van der Waals Materials Research Center, Yonsei University, Seoul, 03722, Republic of Korea
| | - Leeor Kronik
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth, 76100, Israel
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
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20
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Yang J, Sato H, Orio H, Liu X, Fahlman M, Ueno N, Yoshida H, Yamada T, Kera S. Accessing the Conduction Band Dispersion in CH 3NH 3PbI 3 Single Crystals. J Phys Chem Lett 2021; 12:3773-3778. [PMID: 33844910 DOI: 10.1021/acs.jpclett.1c00530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The conduction band dispersion in methylammonium lead iodide (CH3NH3PbI3) was studied by both angle-resolved two-photon photoelectron spectroscopy (AR-2PPE) with low photon intensity (∼0.0125 nJ/pulse) and angle-resolved low-energy inverse photoelectron spectroscopy (AR-LEIPS). Clear energy dispersion of the conduction band along the Γ-M direction was first observed by these independent methods under different temperatures, and the dispersion was found to be consistent with band calculation under the cubic phase. The effective mass of the electrons at the Γ point was estimated to be (0.20 ± 0.05)m0 at the temperature of 90 K. The observed conduction band energy was different between the AR-LEIPS and AR-2PPE, which was ascribed to the electronic-correlation-dependent difference of initial and final states probing processes. The present results also indicate that the surface structure in CH3NH3PbI3 provides the cubic-dominated electronic property even at lower temperatures.
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Affiliation(s)
- Jinpeng Yang
- College of Physical Science and Technology, Yangzhou University, Jiangsu, China
- Department of Photo-Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, Japan
| | - Haruki Sato
- Graduate School of Science and Engineering, Chiba University, Chiba, Japan
| | - Hibiki Orio
- Graduate School of Science and Engineering, Chiba University, Chiba, Japan
| | - Xianjie Liu
- Laboratory for Organic Electronics, ITN, Linköping University, Norrköping, Sweden
| | - Mats Fahlman
- Laboratory for Organic Electronics, ITN, Linköping University, Norrköping, Sweden
| | - Nobuo Ueno
- Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan
| | - Hiroyuki Yoshida
- Graduate School of Engineering, Chiba University, Chiba, Japan
- Molecular Chirality Research Center, Chiba University, Chiba, Japan
| | - Takashi Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Satoshi Kera
- Department of Photo-Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, Japan
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21
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Xu Q, Zhang H, Nie J, Shao W, Wang X, Zhang B, Ouyang X. Effect of methylammonium lead tribromide perovskite based-photoconductor under gamma photons radiation. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109337] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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22
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Schwartz HA, Laurenzen H, Marzouk A, Runkel M, Brinkmann KO, Rogalla D, Riedl T, Ashhab S, Olthof S. Band-Gap Tuning in All-Inorganic CsPb xSn 1-xBr 3 Perovskites. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4203-4210. [PMID: 33435668 DOI: 10.1021/acsami.0c20285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We investigate all-inorganic perovskite CsPbxSn1-xBr3 thin films to determine the variations in the band gap and electronic structure associated with the Pb/Sn ratio. We observe that the band gap can be tuned between 1.86 eV (x = 0) and 2.37 eV (x = 1). Intriguingly, this change is nonlinear in x, with a bowing parameter of 0.9 eV; furthermore, a slight band gap narrowing is found for low Pb content (minimum x ∼ 0.3). The wide tunability of the band gap makes CsPbxSn1-xBr3 a promising material, e.g., for a wide-gap subcell in tandem applications or for color-tunable light-emitting diodes. Employing photoelectron spectroscopy, we show that the valence band varies with the Pb/Sn ratio, while the conduction band is barely affected.
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Affiliation(s)
- Heidi A Schwartz
- Department of Chemistry, University of Cologne, Greinstrasse 4-6, 50939 Cologne, Germany
| | - Hannah Laurenzen
- Department of Chemistry, University of Cologne, Greinstrasse 4-6, 50939 Cologne, Germany
| | - Asma Marzouk
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha 122104, Qatar
| | - Manuel Runkel
- Institute of Electronic Devices and Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany
| | - Kai Oliver Brinkmann
- Institute of Electronic Devices and Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany
| | - Detlef Rogalla
- RUBION, University of Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Thomas Riedl
- Institute of Electronic Devices and Wuppertal Center for Smart Materials & Systems, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany
| | - Sahel Ashhab
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P.O. Box 34110, Doha 122104, Qatar
| | - Selina Olthof
- Department of Chemistry, University of Cologne, Greinstrasse 4-6, 50939 Cologne, Germany
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23
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Mirzehmet A, Ohtsuka T, Abd Rahman SA, Yuyama T, Krüger P, Yoshida H. Surface Termination of Solution-Processed CH 3NH 3PbI 3 Perovskite Film Examined using Electron Spectroscopies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004981. [PMID: 33617084 DOI: 10.1002/adma.202004981] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/19/2020] [Indexed: 05/21/2023]
Abstract
The interfaces of a perovskite solar cell significantly influence the charge processes in the cell, which contributes to the device performance with direct implication for surface potential, electronic structure, and chemical reactivity. The properties of the interface are strongly affected by the surface termination. In this work, the combination of ultraviolet photoelectron spectroscopy (UPS) and metastable-atom electron spectroscopy is demonstrated, to examine the surface termination of a solution-processed CH3NH3PbI3 perovskite film. The results show that the surface of the CH3NH3PbI3 perovskite film is terminated with a layer consisting of CH3NH3 and I. The interface energy level alignment for both occupied and unoccupied levels between CH3NH3PbI3 and C60 is also examined using UPS and low-energy inverse photoelectron spectroscopy. It turns out that an ideal energy level alignment is established for the electron collection and hole block at the perovskite and C60 interface.
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Affiliation(s)
- Abduheber Mirzehmet
- Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Tomoki Ohtsuka
- Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Syed A Abd Rahman
- Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Tomoki Yuyama
- Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Peter Krüger
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
| | - Hiroyuki Yoshida
- Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
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24
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Zhang F, Hamill JC, Loo YL, Kahn A. Gap States in Methylammonium Lead Halides: The Link to Dimethylsulfoxide? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003482. [PMID: 32885516 DOI: 10.1002/adma.202003482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 08/07/2020] [Indexed: 06/11/2023]
Abstract
Understanding the origin and distribution of electronic gap states in metal halide perovskite (MHP) thin films is crucial to the further improvement of the efficiency and long-term stability of MHP-based optoelectronic devices. In this work, the impact of Lewis-basic additives introduced in the precursor solution on the density of states in the perovskite bandgap is investigated. Ultraviolet photoemission spectroscopy and contact potential difference measurements are conducted on MHP thin films processed from dimethylformamide (DMF)-based solutions to which either no additive, dimethylsulfoxide (DMSO), or N-methylpyrrolidine-2-thione (NMPT) is added. The results show the presence of a density of states in the gap of methylammonium lead halide films processed from DMSO-containing solution. The density of gap states is either suppressed when the methylammonium concentration in mixed cation films is reduced or when NMPT is used as an additive, and eliminated when methylammonium (MA) is replaced with cesium or formamidinium (FA). These results are consistent with the notion that reaction products that result from DMSO reacting with MA+ in the precursor solution are responsible for the formation of gap states.
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Affiliation(s)
- Fengyu Zhang
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - J Clay Hamill
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Yueh-Lin Loo
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, 08544, USA
| | - Antoine Kahn
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
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25
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Angle-Resolved Photoemission Study on the Band Structure of Organic Single Crystals. CRYSTALS 2020. [DOI: 10.3390/cryst10090773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Angle-resolved photoemission spectroscopy (ARPES) is a vital technique, collecting data from both the energy and momentum of photoemitted electrons, and is indispensable for investigating the electronic band structure of solids. This article provides a review on ARPES studies of the electronic band structure of organic single crystals, including organic charge transfer conductors; organic semiconductors; and organo-metallic perovskites. In organic conductors and semiconductors, band dispersions are observed that are highly anisotropic. The Van der Waals crystal nature, the weak electron wavefunction overlap, as well as the strong electron-phonon coupling result in many organic crystals having indiscernible dispersion. In comparison, organo-metallic perovskite halides are characterized by strong s-p orbitals from the metal and halide at the top of the valence bands, with dispersions similar to those in inorganic materials.
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26
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Lim AR, Kim SH, Joo YL. Structural dynamics of CH 3NH 3+ and PbBr 3- in tetragonal and cubic phases of CH 3NH 3PbBr 3 hybrid perovskite by nuclear magnetic resonance. Sci Rep 2020; 10:13140. [PMID: 32753613 PMCID: PMC7403148 DOI: 10.1038/s41598-020-70128-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/20/2020] [Indexed: 11/09/2022] Open
Abstract
Understanding the structural dynamics of lead-halide perovskites is essential for their advanced use as photovoltaics. Here, the structural dynamics of the CH3NH3 cation and PbBr6 octahedra in the perovskite CH3NH3PbBr3 were studied via nuclear magnetic resonance (NMR) to determine the mechanism of the transition from the tetragonal to cubic phase. The chemical shifts were obtained by 1H, 13C, and 207Pb magic angle spinning NMR and 14N static NMR. The chemical shifts of the 1H nuclei in CH3 and NH3 remained constant with increasing temperature, whereas those of the 13C and 207Pb nuclei varied near the phase transition temperature (TC = 236 K), indicating that the structural environments of 13C and 207Pb change near TC. The spin-lattice relaxation time T1ρ values for 1H, 13C, and 207Pb nuclei increased with increasing temperature and did not exhibit an abrupt change near TC. In addition, the two lines in the 14N NMR spectra superposed into one line near TC, indicating the occurrence of a phase transition to a cubic phase with higher symmetry than tetragonal. Consequently, the main factor causing the phase transition from the tetragonal to cubic phase near TC is a change in the surroundings of the 207Pb nuclei in the PbBr6 octahedra and of the C-N groups in the CH3NH3 cations.
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Affiliation(s)
- Ae Ran Lim
- Analytical Laboratory of Advanced Ferroelectric Crystals, Department of Science Education, Jeonju University, Jeonju, 55069, Korea.
| | - Sun Ha Kim
- Seoul Western Center, Korea Basic Science Institute, Seoul, 03759, Korea
- Department of Chemistry, Kyungpook National University, Daegu, 41566, Korea
| | - Yong Lak Joo
- Robert Fredrick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
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27
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Franco-Cañellas A, Duhm S, Gerlach A, Schreiber F. Binding and electronic level alignment of π-conjugated systems on metals. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2020; 83:066501. [PMID: 32101802 DOI: 10.1088/1361-6633/ab7a42] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We review the binding and energy level alignment of π-conjugated systems on metals, a field which during the last two decades has seen tremendous progress both in terms of experimental characterization as well as in the depth of theoretical understanding. Precise measurements of vertical adsorption distances and the electronic structure together with ab initio calculations have shown that most of the molecular systems have to be considered as intermediate cases between weak physisorption and strong chemisorption. In this regime, the subtle interplay of different effects such as covalent bonding, charge transfer, electrostatic and van der Waals interactions yields a complex situation with different adsorption mechanisms. In order to establish a better understanding of the binding and the electronic level alignment of π-conjugated molecules on metals, we provide an up-to-date overview of the literature, explain the fundamental concepts as well as the experimental techniques and discuss typical case studies. Thereby, we relate the geometric with the electronic structure in a consistent picture and cover the entire range from weak to strong coupling.
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Affiliation(s)
- Antoni Franco-Cañellas
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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28
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Dynamic processes involving inorganic solids. Inorg Chem 2020. [DOI: 10.1016/b978-0-12-814369-8.00008-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Zu F, Schultz T, Wolff CM, Shin D, Frohloff L, Neher D, Amsalem P, Koch N. Position-locking of volatile reaction products by atmosphere and capping layers slows down photodecomposition of methylammonium lead triiodide perovskite. RSC Adv 2020; 10:17534-17542. [PMID: 35515637 PMCID: PMC9053590 DOI: 10.1039/d0ra03572f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 04/23/2020] [Indexed: 11/21/2022] Open
Abstract
The remarkable progress of metal halide perovskites in photovoltaics has led to the power conversion efficiency approaching 26%. However, practical applications of perovskite-based solar cells are challenged by the stability issues, of which the most critical one is photo-induced degradation. Bare CH3NH3PbI3 perovskite films are known to decompose rapidly, with methylammonium and iodine as volatile species and residual solid PbI2 and metallic Pb, under vacuum under white light illumination, on the timescale of minutes. We find, in agreement with previous work, that the degradation is non-uniform and proceeds predominantly from the surface, and that illumination under N2 and ambient air (relative humidity 20%) does not induce substantial degradation even after several hours. Yet, in all cases the release of iodine from the perovskite surface is directly identified by X-ray photoelectron spectroscopy. This goes in hand with a loss of organic cations and the formation of metallic Pb. When CH3NH3PbI3 films are covered with a few nm thick organic capping layer, either charge selective or non-selective, the rapid photodecomposition process under ultrahigh vacuum is reduced by more than one order of magnitude, and becomes similar in timescale to that under N2 or air. We conclude that the light-induced decomposition reaction of CH3NH3PbI3, leading to volatile methylammonium and iodine, is largely reversible as long as these products are restrained from leaving the surface. This is readily achieved by ambient atmospheric pressure, as well as a thin organic capping layer even under ultrahigh vacuum. In addition to explaining the impact of gas pressure on the stability of this perovskite, our results indicate that covalently “locking” the position of perovskite components at the surface or an interface should enhance the overall photostability. Gas pressure and capping layers under ultrahigh vacuum prevent methylammonium lead triiodide photo-degradation due to efficient back-reaction of volatile compounds.![]()
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Affiliation(s)
- Fengshuo Zu
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Thorsten Schultz
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
| | - Christian M. Wolff
- Institut für Physik und Astronomie
- Universität Potsdam
- 14776 Potsdam
- Germany
| | - Dongguen Shin
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Lennart Frohloff
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Dieter Neher
- Institut für Physik und Astronomie
- Universität Potsdam
- 14776 Potsdam
- Germany
| | - Patrick Amsalem
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
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30
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Wolff CM, Caprioglio P, Stolterfoht M, Neher D. Nonradiative Recombination in Perovskite Solar Cells: The Role of Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1902762. [PMID: 31631441 DOI: 10.1002/adma.201902762] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 08/19/2019] [Indexed: 05/05/2023]
Abstract
Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their VOC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the VOC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome-paving the way to the thermodynamic efficiency limit.
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Affiliation(s)
- Christian M Wolff
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Pietro Caprioglio
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie, Young Investigator Group Perovskite Tandem Solar Cells, Kekuléstraße 5, 12489, Berlin, Germany
| | - Martin Stolterfoht
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Dieter Neher
- Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
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31
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Zu F, Wolff CM, Ralaiarisoa M, Amsalem P, Neher D, Koch N. Unraveling the Electronic Properties of Lead Halide Perovskites with Surface Photovoltage in Photoemission Studies. ACS APPLIED MATERIALS & INTERFACES 2019; 11:21578-21583. [PMID: 31124647 DOI: 10.1021/acsami.9b05293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The tremendous success of metal-halide perovskites, especially in the field of photovoltaics, has triggered a substantial number of studies in understanding their optoelectronic properties. However, consensus regarding the electronic properties of these perovskites is lacking due to a huge scatter in the reported key parameters, such as work function (Φ) and valence band maximum (VBM) values. Here, we demonstrate that the surface photovoltage (SPV) is a key phenomenon occurring at the perovskite surfaces that feature a non-negligible density of surface states, which is more the rule than an exception for most materials under study. With ultraviolet photoelectron spectroscopy (UPS) and Kelvin probe, we evidence that even minute UV photon fluxes (500 times lower than that used in typical UPS experiments) are sufficient to induce SPV and shift the perovskite Φ and VBM by several 100 meV compared to dark. By combining UV and visible light, we establish flat band conditions (i.e., compensate the surface-state-induced surface band bending) at the surface of four important perovskites, and find that all are p-type in the bulk, despite a pronounced n-type surface character in the dark. The present findings highlight that SPV effects must be considered in all surface studies to fully understand perovskites' photophysical properties.
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Affiliation(s)
- Fengshuo Zu
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
| | - Christian M Wolff
- Institut für Physik und Astronomie , Universität Potsdam , 14776 Potsdam , Germany
| | - Maryline Ralaiarisoa
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
| | - Patrick Amsalem
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
| | - Dieter Neher
- Institut für Physik und Astronomie , Universität Potsdam , 14776 Potsdam , Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
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