1
|
Li Q, Wu K, Zhu H, Yang Y, He S, Lian T. Charge Transfer from Quantum-Confined 0D, 1D, and 2D Nanocrystals. Chem Rev 2024; 124:5695-5763. [PMID: 38629390 PMCID: PMC11082908 DOI: 10.1021/acs.chemrev.3c00742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 03/29/2024] [Accepted: 04/02/2024] [Indexed: 05/09/2024]
Abstract
The properties of colloidal quantum-confined semiconductor nanocrystals (NCs), including zero-dimensional (0D) quantum dots, 1D nanorods, 2D nanoplatelets, and their heterostructures, can be tuned through their size, dimensionality, and material composition. In their photovoltaic and photocatalytic applications, a key step is to generate spatially separated and long-lived electrons and holes by interfacial charge transfer. These charge transfer properties have been extensively studied recently, which is the subject of this Review. The Review starts with a summary of the electronic structure and optical properties of 0D-2D nanocrystals, followed by the advances in wave function engineering, a novel way to control the spatial distribution of electrons and holes, through their size, dimension, and composition. It discusses the dependence of NC charge transfer on various parameters and the development of the Auger-assisted charge transfer model. Recent advances in understanding multiple exciton generation, decay, and dissociation are also discussed, with an emphasis on multiple carrier transfer. Finally, the applications of nanocrystal-based systems for photocatalysis are reviewed, focusing on the photodriven charge separation and recombination processes that dictate the function and performance of these materials. The Review ends with a summary and outlook of key remaining challenges and promising future directions in the field.
Collapse
Affiliation(s)
- Qiuyang Li
- Department
of Physics, University of Michigan, 450 Church St, Ann Arbor, Michigan 48109, United States
| | - Kaifeng Wu
- State
Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation
Center of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiming Zhu
- Department
of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Ye Yang
- The
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM
(Collaborative Innovation Center of Chemistry for Energy Materials),
College of Chemistry & Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Sheng He
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| |
Collapse
|
2
|
Abstract
Lasers and optical amplifiers based on solution-processable materials have been long-desired devices for their compatibility with virtually any substrate, scalability, and ease of integration with on-chip photonics and electronics. These devices have been pursued across a wide range of materials including polymers, small molecules, perovskites, and chemically prepared colloidal semiconductor nanocrystals, also commonly referred to as colloidal quantum dots. The latter materials are especially attractive for implementing optical-gain media as in addition to being compatible with inexpensive and easily scalable chemical techniques, they offer multiple advantages derived from a zero-dimensional character of their electronic states. These include a size-tunable emission wavelength, low optical gain thresholds, and weak sensitivity of lasing characteristics to variations in temperature. Here we review the status of colloidal nanocrystal lasing devices, most recent advances in this field, outstanding challenges, and the ongoing progress toward technological viable devices including colloidal quantum dot laser diodes.
Collapse
Affiliation(s)
- Namyoung Ahn
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Clément Livache
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Valerio Pinchetti
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| |
Collapse
|
3
|
Vonk SJW, Rabouw FT. Biexciton Blinking in CdSe-Based Quantum Dots. J Phys Chem Lett 2023:5353-5361. [PMID: 37276380 DOI: 10.1021/acs.jpclett.3c00437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Experiments on single colloidal quantum dots (QDs) have revealed temporal fluctuations in the emission efficiency of the single-exciton state. These fluctuations, often termed "blinking", are caused by opening/closing of charge-carrier traps and/or charging/discharging of the QD. In the regime of strong optical excitation, multiexciton states are formed. The emission efficiencies of multiexcitons are lower because of Auger processes, but a quantitative characterization is challenging. Here, we quantify fluctuations of the biexciton efficiency for single CdSe/CdS/ZnS core-shell QDs. We find that the biexciton efficiency "blinks" significantly. The additional electron due to charging of a QD accelerates Auger recombination by a factor of 2 compared to the neutral biexciton, while opening/closing of a charge-carrier trap leads to an increase of the nonradiative recombination rate by a factor of 4. To understand the fast rate of trap-assisted recombination, we propose a revised model for trap-assisted recombination based on reversible trapping. Finally, we discuss the implications of biexciton blinking for lasing applications.
Collapse
Affiliation(s)
- Sander J W Vonk
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| |
Collapse
|
4
|
Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission. Nat Commun 2022; 13:5094. [PMID: 36042249 PMCID: PMC9427944 DOI: 10.1038/s41467-022-32713-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Nanocrystals (NCs) are now established building blocks for optoelectronics and their use as down converters for large gamut displays has been their first mass market. NC integration relies on a combination of green and red NCs into a blend, which rises post-growth formulation issues. A careful engineering of the NCs may enable dual emissions from a single NC population which violates Kasha’s rule, which stipulates that emission should occur at the band edge. Thus, in addition to an attentive control of band alignment to obtain green and red signals, non-radiative decay paths also have to be carefully slowed down to enable emission away from the ground state. Here, we demonstrate that core/crown/crown 2D nanoplatelets (NPLs), made of CdSe/CdTe/CdSe, can combine a large volume and a type-II band alignment enabling simultaneously red and narrow green emissions. Moreover, we demonstrate that the ratio of the two emissions can be tuned by the incident power, which results in a saturation of the red emission due to non-radiative Auger recombination that affects this emission much stronger than the green one. Finally, we also show that dual-color, power tunable, emission can be obtained through an electrical excitation. Nanocrystals are desirable light sources for advanced display technologies. Here, the authors report on double-crowned 2D semiconductor nanoplatelets as light downconverters that offer both green and red emissions to achieve a wide color gamut.
Collapse
|
5
|
Lee Y, Jo DY, Kim T, Jo JH, Park J, Yang H, Kim D. Effectual Interface and Defect Engineering for Auger Recombination Suppression in Bright InP/ZnSeS/ZnS Quantum Dots. ACS APPLIED MATERIALS & INTERFACES 2022; 14:12479-12487. [PMID: 35238532 DOI: 10.1021/acsami.1c20088] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The main issue in developing a quantum dot light-emitting diode (QLED) display lies in successfully replacing heavy metals with environmentally benign materials while maintaining high-quality device performance. Nonradiative Auger recombination is one of the major limiting factors of QLED performance and should ideally be suppressed. This study scrutinizes the effects of the shell structure and composition on photoluminescence (PL) properties of InP/ZnSeS/ZnS quantum dots (QDs) through ensemble and single-dot spectroscopic analyses. Employing gradient shells is discovered to suppress Auger recombination to a high degree, allowing charged QDs to be luminescent comparatively with neutral QDs. The "lifetime blinking" phenomenon is observed as evidence of suppressed Auger recombination. Furthermore, single-QD measurements reveal that gradient shells in QDs reduce spectral diffusion and elevate the energy barrier for charge trapping. Shell composition dependency in the gradience effect is observed. An increase in the ZnS composition (ZnS >50%) in the gradient shell introduces lattice mismatch between the core and the shell and therefore rather reverses the effect and reduces the QD performance.
Collapse
Affiliation(s)
- YuJin Lee
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Dae-Yeon Jo
- Department of Materials Science and Engineering, Hongik University, 94 Wausan-ro, Mapo-gu, Seoul 04066, Republic of Korea
| | - Taehee Kim
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Jung-Ho Jo
- Department of Materials Science and Engineering, Hongik University, 94 Wausan-ro, Mapo-gu, Seoul 04066, Republic of Korea
| | - Jumi Park
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| | - Heesun Yang
- Department of Materials Science and Engineering, Hongik University, 94 Wausan-ro, Mapo-gu, Seoul 04066, Republic of Korea
| | - Dongho Kim
- Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea
| |
Collapse
|
6
|
Affiliation(s)
- Christopher Melnychuk
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | | |
Collapse
|
7
|
Kagan CR, Bassett LC, Murray CB, Thompson SM. Colloidal Quantum Dots as Platforms for Quantum Information Science. Chem Rev 2020; 121:3186-3233. [DOI: 10.1021/acs.chemrev.0c00831] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
8
|
Porotnikov D, Diroll BT, Harankahage D, Obloy L, Yang M, Cassidy J, Ellison C, Miller E, Rogers S, Tarnovsky AN, Schaller RD, Zamkov M. Low-threshold laser medium utilizing semiconductor nanoshell quantum dots. NANOSCALE 2020; 12:17426-17436. [PMID: 32797122 DOI: 10.1039/d0nr03582c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal semiconductor nanocrystals (NCs) represent a promising class of nanomaterials for lasing applications. Currently, one of the key challenges facing the development of high-performance NC optical gain media lies in enhancing the lifetime of biexciton populations. This usually requires the employment of charge-delocalizing particle architectures, such as core/shell NCs, nanorods, and nanoplatelets. Here, we report on a two-dimensional nanoshell quantum dot (QD) morphology that enables a strong delocalization of photoinduced charges, leading to enhanced biexciton lifetimes and low lasing thresholds. A unique combination of a large exciton volume and a smoothed potential gradient across interfaces of the reported CdSbulk/CdSe/CdSshell (core/shell/shell) nanoshell QDs results in strong suppression of Auger processes, which was manifested in this work though the observation of stable amplified stimulated emission (ASE) at low pump fluences. An extensive charge delocalization in nanoshell QDs was confirmed by transient absorption measurements, showing that the presence of a bulk-size core in CdSbulk/CdSe/CdSshell QDs reduces exciton-exciton interactions. Overall, present findings demonstrate unique advantages of the nanoshell QD architecture as a promising optical gain medium in solid-state lighting and lasing applications.
Collapse
Affiliation(s)
- Dmitry Porotnikov
- The Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Morozov S, Pensa EL, Khan AH, Polovitsyn A, Cortés E, Maier SA, Vezzoli S, Moreels I, Sapienza R. Electrical control of single-photon emission in highly charged individual colloidal quantum dots. SCIENCE ADVANCES 2020; 6:6/38/eabb1821. [PMID: 32948584 PMCID: PMC7500932 DOI: 10.1126/sciadv.abb1821] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 07/27/2020] [Indexed: 05/30/2023]
Abstract
Electron transfer to an individual quantum dot promotes the formation of charged excitons with enhanced recombination pathways and reduced lifetimes. Excitons with only one or two extra charges have been observed and exploited for very efficient lasing or single-quantum dot light-emitting diodes. Here, by room-temperature time-resolved experiments on individual giant-shell CdSe/CdS quantum dots, we show the electrochemical formation of highly charged excitons containing more than 12 electrons and 1 hole. We report the control over intensity blinking, along with a deterministic manipulation of quantum dot photodynamics, with an observed 210-fold increase in the decay rate, accompanied by 12-fold decrease in the emission intensity, while preserving single-photon emission characteristics. These results pave the way for deterministic control over the charge state, and room-temperature decay rate engineering for colloidal quantum dot-based classical and quantum communication technologies.
Collapse
Affiliation(s)
- Sergii Morozov
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK
| | - Evangelina L Pensa
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK
| | - Ali Hossain Khan
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, Gent 9000, Belgium
| | - Anatolii Polovitsyn
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, Gent 9000, Belgium
| | - Emiliano Cortés
- Chair in Hybrid Nanosystems, Nano-Institute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, München 80539, Germany
| | - Stefan A Maier
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK
- Chair in Hybrid Nanosystems, Nano-Institute Munich, Faculty of Physics, Ludwig-Maxilimians-Universität München, München 80539, Germany
| | - Stefano Vezzoli
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, Gent 9000, Belgium
| | - Riccardo Sapienza
- The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2BW, UK.
| |
Collapse
|
10
|
Khan Q, Subramanian A, Yu G, Maaz K, Li D, Sagar RUR, Chen K, Lei W, Shabbir B, Zhang Y. Structure optimization of perovskite quantum dot light-emitting diodes. NANOSCALE 2019; 11:5021-5029. [PMID: 30839976 DOI: 10.1039/c8nr09864f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Although all-inorganic perovskite light emitting diodes (PeLED) have satisfactory stability under an ambient atmosphere, producing devices with high performance is challenging. A device architecture with a reduced energy barrier between adjacent layers and optimized energy level alignment in the PeLED is critical to achieve high electroluminescence efficiency. In this study, we report the optimization of a CsPbBr3-based PeLED device structure with Li-doped TiO2 nanoparticles as the electron transport layer (ETL). Optimal Li doping balances charge carrier injection between the hole transport layer (HTL) and ETL, leading to superior performance in both devices. The turn-on voltages for devices with Li-doped TiO2 nanoparticles were significantly reduced from 7.7 V to 4.9 V and from 3 V to 2 V in the direct and inverted PeLED structures, respectively. The low turn-on voltage for green emission is one of the lowest values among the reported CsPbBr3-based PeLEDs. Further investigations show that the device with an inverted structure is superior to the device with a direct structure because the energy barrier for carrier injection was minimized. The inverted structure devices exhibited a current efficiency of 5.6 cd A-1 for the pristine TiO2 ETL, while it was 15.2 cd A-1 for the Li-doped TiO2 ETL, a factor of ∼2.7 enhancement at 5000 cd m-2.
Collapse
Affiliation(s)
- Qasim Khan
- Shenzhen Key Laboratory of Flexible Memory Materials and Devices, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518000, China.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
|
12
|
Lim J, Park YS, Wu K, Yun HJ, Klimov VI. Droop-Free Colloidal Quantum Dot Light-Emitting Diodes. NANO LETTERS 2018; 18:6645-6653. [PMID: 30198267 DOI: 10.1021/acs.nanolett.8b03457] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Colloidal semiconductor quantum dots (QDs) are a highly promising materials platform for implementing solution-processable light-emitting diodes (LEDs). They combine high photostability of traditional inorganic semiconductors with chemical flexibility of molecular systems, which makes them well-suited for large-area applications such as television screens, solid-state lighting, and outdoor signage. Additional beneficial features include size-controlled emission wavelengths, narrow bandwidths, and nearly perfect emission efficiencies. State-of-the-art QD-LEDs exhibit high internal quantum efficiencies approaching unity. However, these peak values are observed only at low current densities ( J) and correspondingly low brightnesses, whereas at higher J, the efficiency usually exhibits a quick roll-off. This efficiency droop limits achievable brightness levels and decreases device longevity due to excessive heat generation. Here, we demonstrate QD-LEDs operating with high internal efficiencies (up to 70%) virtually droop-free up to unprecedented brightness of >100,000 cd m-2 (at ∼500 mA cm-2). This exceptional performance is derived from specially engineered QDs that feature a compositionally graded interlayer and a final barrier layer. This QD design allows for improved balance between electron and hole injections combined with considerably suppressed Auger recombination, which helps mitigate efficiency losses due to charge imbalance at high currents. These results indicate a significant potential of newly developed QDs as enablers of future ultrabright, highly efficient devices for both indoor and outdoor applications.
Collapse
Affiliation(s)
- Jaehoon Lim
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
- Department of Chemical Engineering & Department of Energy System Research , Ajou University , Suwon 16499 , Republic of Korea
| | - Young-Shin Park
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
- Center for High Technology Materials , University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Kaifeng Wu
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Hyeong Jin Yun
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Victor I Klimov
- Chemistry Division , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| |
Collapse
|
13
|
Chen Z, Li Z, Zhang C, Jiang XF, Chen D, Xue Q, Liu M, Su S, Yip HL, Cao Y. Recombination Dynamics Study on Nanostructured Perovskite Light-Emitting Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801370. [PMID: 30088297 DOI: 10.1002/adma.201801370] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/21/2018] [Indexed: 06/08/2023]
Abstract
The field of organic-inorganic hybrid perovskite light-emitting diodes (PeLEDs) has developed rapidly in recent years. Although the performance of PeLEDs continues to improve through film quality control and device optimization, little research has been dedicated to understanding the recombination dynamics in perovskite thin films. Likewise, little has been done to investigate the effects of recombination dynamics on the overall light-emitting behavior of PeLEDs. Therefore, this study investigates the recombination dynamics of CH3 NH3 PbI3 thin films with differing crystal sizes by measurement of fluence-dependent transient absorption dynamics and time-resolved photoluminescence. The aim is to find out the link between recombination dynamics and device behavior in PeLEDs. It is found that bimolecular and Auger recombination become more efficient as the crystal size decreases and monomolecular recombination rate is affected by the trap density of perovskite. By defining the radiative efficiency Φ(n), which relates to the monomolecular, bimolecular, and Auger recombination, the fundamental recombination properties of CH3 NH3 PbI3 films are discerned in quantitative terms. These findings help us to understand the light emission behavior of PeLEDs. This study takes an important step toward establishing the relationship between film structure, recombination dynamics, and device behavior for PeLEDs, thereby providing useful insights toward the design of better perovskite devices.
Collapse
Affiliation(s)
- Ziming Chen
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Zhenchao Li
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Chongyang Zhang
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Xiao-Fang Jiang
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Dongcheng Chen
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Qifan Xue
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Meiyue Liu
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Shijian Su
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Hin-Lap Yip
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| | - Yong Cao
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, P. R. China
| |
Collapse
|
14
|
Subramanian A, Pan Z, Zhang Z, Ahmad I, Chen J, Liu M, Cheng S, Xu Y, Wu J, Lei W, Khan Q, Zhang Y. Interfacial Energy-Level Alignment for High-Performance All-Inorganic Perovskite CsPbBr 3 Quantum Dot-Based Inverted Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:13236-13243. [PMID: 29601175 DOI: 10.1021/acsami.8b01684] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
All-inorganic perovskite light-emitting diode (PeLED) has a high stability in ambient atmosphere, but it is a big challenge to achieve high performance of the device. Basically, device design, control of energy-level alignment, and reducing the energy barrier between adjacent layers in the architecture of PeLED are important factors to achieve high efficiency. In this study, we report a CsPbBr3-based PeLED with an inverted architecture using lithium-doped TiO2 nanoparticles as the electron transport layer (ETL). The optimal lithium doping balances the charge carrier injection between the hole transport layer and ETL, leading to superior device performance. The device exhibits a current efficiency of 3 cd A-1, a luminance efficiency of 2210 cd m-2, and a low turn-on voltage of 2.3 V. The turn-on voltage is one of the lowest values among reported CsPbBr3-based PeLEDs. A 7-fold increase in device efficiencies has been obtained for lithium-doped TiO2 compared to that for undoped TiO2-based devices.
Collapse
Affiliation(s)
- Alagesan Subramanian
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Zhenghui Pan
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Zhenbo Zhang
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Imtiaz Ahmad
- Department of Applied Chemistry , Xi'an Jiaotong-Liverpool University , Suzhou , Jiangsu 215123 , China
| | - Jing Chen
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Meinan Liu
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Shuang Cheng
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Yijun Xu
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
| | - Jun Wu
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Wei Lei
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Qasim Khan
- Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering , Southeast University , Nanjing , Jiangsu 210096 , China
| | - Yuegang Zhang
- i-Lab , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou , Jiangsu 215123 , China
- Department of Physics , Tsinghua University , Beijing 100084 , China
| |
Collapse
|
15
|
Panfil YE, Oded M, Banin U. Colloidal Quantum Nanostructures: Emerging Materials for Display Applications. Angew Chem Int Ed Engl 2018; 57:4274-4295. [PMID: 28975692 PMCID: PMC6001641 DOI: 10.1002/anie.201708510] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Indexed: 11/11/2022]
Abstract
Colloidal semiconductor nanocrystals (SCNCs) or, more broadly, colloidal quantum nanostructures constitute outstanding model systems for investigating size and dimensionality effects. Their nanoscale dimensions lead to quantum confinement effects that enable tuning of their optical and electronic properties. Thus, emission color control with narrow photoluminescence spectra, wide absorbance spectra, and outstanding photostability, combined with their chemical processability through control of their surface chemistry leads to the emergence of SCNCs as outstanding materials for present and next-generation displays. In this Review, we present the fundamental chemical and physical properties of SCNCs, followed by a description of the advantages of different colloidal quantum nanostructures for display applications. The open challenges with respect to their optical activity are addressed. Both photoluminescent and electroluminescent display scenarios utilizing SCNCs are described.
Collapse
Affiliation(s)
- Yossef E. Panfil
- Institute of Chemistry and the Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem9190401Israel
| | - Meirav Oded
- Institute of Chemistry and the Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem9190401Israel
| | - Uri Banin
- Institute of Chemistry and the Center for Nanoscience and NanotechnologyThe Hebrew University of JerusalemJerusalem9190401Israel
| |
Collapse
|
16
|
Panfil YE, Oded M, Banin U. Kolloidale Quantennanostrukturen: neue Materialien für Displayanwendungen. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201708510] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yossef E. Panfil
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem; Jerusalem 9190401 Israel
| | - Meirav Oded
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem; Jerusalem 9190401 Israel
| | - Uri Banin
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology; The Hebrew University of Jerusalem; Jerusalem 9190401 Israel
| |
Collapse
|
17
|
Park K, Kuo Y, Shvadchak V, Ingargiola A, Dai X, Hsiung L, Kim W, Zhou H, Zou P, Levine AJ, Li J, Weiss S. Membrane insertion of-and membrane potential sensing by-semiconductor voltage nanosensors: Feasibility demonstration. SCIENCE ADVANCES 2018; 4:e1601453. [PMID: 29349292 PMCID: PMC5770167 DOI: 10.1126/sciadv.1601453] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 12/08/2017] [Indexed: 05/22/2023]
Abstract
We developed membrane voltage nanosensors that are based on inorganic semiconductor nanoparticles. We provide here a feasibility study for their utilization. We use a rationally designed peptide to functionalize the nanosensors, imparting them with the ability to self-insert into a lipid membrane with a desired orientation. Once inserted, these nanosensors could sense membrane potential via the quantum confined Stark effect, with a single-particle sensitivity. With further improvements, these nanosensors could potentially be used for simultaneous recording of action potentials from multiple neurons in a large field of view over a long duration and for recording electrical signals on the nanoscale, such as across one synapse.
Collapse
Affiliation(s)
- Kyoungwon Park
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yung Kuo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Volodymyr Shvadchak
- Institute of Organic Chemistry and Biochemistry AS CR, Prague 166-10, Czech Republic
| | - Antonino Ingargiola
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xinghong Dai
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lawrence Hsiung
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Wookyeom Kim
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peng Zou
- Department of Chemistry and Chemical Biology, Harvard University, MA 02138, USA
| | - Alex J. Levine
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jack Li
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Corresponding author.
| |
Collapse
|
18
|
Quintero-Bermudez R, Sabatini RP, Lejay M, Voznyy O, Sargent EH. Small-Band-Offset Perovskite Shells Increase Auger Lifetime in Quantum Dot Solids. ACS NANO 2017; 11:12378-12384. [PMID: 29227680 DOI: 10.1021/acsnano.7b06363] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Colloidal quantum dots (CQDs) enable low-cost, high-performance optoelectronic devices including photovoltaics, photodetectors, LEDs, and lasers. Continuous-wave lasing in the near-infrared remains to be realized based on such materials, yet a solution-processed NIR laser would be of use in communications and interconnects. In infrared quantum dots, long-lived gain is hampered by a high rate of Auger recombination. Here, we report the use of perovskite shells, grown on cores of IR-emitting PbS CQDs, and we thus reduce the rate of Auger recombination by up to 1 order of magnitude. We employ ultrafast transient absorption spectroscopy to isolate distinct Auger recombination phenomena and study the effect of bandstructure and passivation on Auger recombination. We corroborate the experimental findings with model-based investigations of Auger recombination in various CQD core-shell structures. We explain how the band alignment provided by perovskite shells comes close to the optimal required to suppress the Auger rate. These results provide a step along the path toward solution-processed near-infrared lasers.
Collapse
Affiliation(s)
- Rafael Quintero-Bermudez
- Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| | - Randy P Sabatini
- Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| | - Marc Lejay
- Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| | - Oleksandr Voznyy
- Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| |
Collapse
|
19
|
Slonopas A, Tomkinson D. Study of the Natural Auger Suppression Mechanism in Heterostructures through Heteroboundary Engineering. J Phys Chem A 2017; 121:7745-7750. [PMID: 28949549 DOI: 10.1021/acs.jpca.7b07727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Planar superlattice devices revolutionized our approach to solid-state technology by reducing the Shockley-Read-Hall losses to negligible levels. Despite these achievements, significant efficiency losses are found in current devices presumably caused by the Auger recombinations. This work present the theoretical considerations of the Auger recombination suppression through heterostructure engineering. It is found that Auger recombinations are suppressed through the heterobarrier-carrier interactions. It is shown that a minima in Auger recombinations exists in type-II and III heterostructures, and can be reached through proper conduction and valence band alignments. Furthermore, the careful consideration of the heterostructure enables natural Auger suppression for high operating temperatures. Dark current based on the optimized heterostructure was computed and found to be over an order of magnitude below the currently reported measurements for the superlattice and QD devices. This research provides crucial information about the underlying physics behind the Auger recombination, enabling future superlattice and quantum dot device optimization.
Collapse
Affiliation(s)
- Andre Slonopas
- U.S. Army Night Vision and Electronic Sensors Directorate , Fort Belvoir, Virginia 22060, United States
| | - David Tomkinson
- U.S. Army Night Vision and Electronic Sensors Directorate , Fort Belvoir, Virginia 22060, United States
| |
Collapse
|
20
|
Park YS, Lim J, Makarov NS, Klimov VI. Effect of Interfacial Alloying versus "Volume Scaling" on Auger Recombination in Compositionally Graded Semiconductor Quantum Dots. NANO LETTERS 2017; 17:5607-5613. [PMID: 28776995 DOI: 10.1021/acs.nanolett.7b02438] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Auger recombination is a nonradiative three-particle process wherein the electron-hole recombination energy dissipates as a kinetic energy of a third carrier. Auger decay is enhanced in quantum-dot (QD) forms of semiconductor materials compared to their bulk counterparts. Because this process is detrimental to many prospective applications of the QDs, the development of effective approaches for suppressing Auger recombination has been an important goal in the QD field. One such approach involves "smoothing" of the confinement potential, which suppresses the intraband transition involved in the dissipation of the electron-hole recombination energy. The present study evaluates the effect of increasing "smoothness" of the confinement potential on Auger decay employing a series of CdSe/CdS-based QDs wherein the core and the shell are separated by an intermediate layer of a CdSexS1-x alloy comprised of 1-5 sublayers with a radially tuned composition. As inferred from single-dot measurements, use of the five-step grading scheme allows for strong suppression of Auger decay for both biexcitons and charged excitons. Further, due to nearly identical emissivities of neutral and charged excitons, these QDs exhibit an interesting phenomenon of lifetime blinking for which random fluctuations of a photoluminescence lifetime occur for a nearly constant emission intensity.
Collapse
Affiliation(s)
- Young-Shin Park
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Jaehoon Lim
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Nikolay S Makarov
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| |
Collapse
|
21
|
Wu K, Lim J, Klimov VI. Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots. ACS NANO 2017; 11:8437-8447. [PMID: 28723072 DOI: 10.1021/acsnano.7b04079] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdS QDs with two distinct core/shell interfacial profiles ("sharp" versus "smooth"). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. By comparing the measurements on the QDs with the "sharp" versus "smooth" interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. These findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states, suggesting its generality to quantum-confined nanocrystals of arbitrary compositions and complexities.
Collapse
Affiliation(s)
- Kaifeng Wu
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- State Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian 116023, China
| | - Jaehoon Lim
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| |
Collapse
|
22
|
Park K, Weiss S. Design Rules for Membrane-Embedded Voltage-Sensing Nanoparticles. Biophys J 2017; 112:703-713. [PMID: 28256230 PMCID: PMC5340176 DOI: 10.1016/j.bpj.2016.12.047] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/15/2016] [Accepted: 12/28/2016] [Indexed: 11/20/2022] Open
Abstract
Voltage-sensing dyes and voltage-sensing fluorescence proteins have been continually improved and as a result have provided a wealth of insights into neuronal circuits. Further improvements in voltage-sensing dyes and voltage-sensing fluorescence proteins are needed, however, for routine detection of single action potentials across a large number of individual neurons in a large field-of-view of a live mammalian brain. On the other hand, recent experiments and calculations suggest that semiconducting nanoparticles could act as efficient voltage sensors, suitable for the above-mentioned task. This study presents quantum mechanical calculations, including Auger recombination rates, of the quantum-confined Stark effect in membrane-embedded semiconducting nanoparticles, examines their possible utility as membrane voltage sensors, and provide design rules for their structure and composition.
Collapse
Affiliation(s)
- Kyoungwon Park
- Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California; Department of Physiology, University of California Los Angeles, Los Angeles, California; California NanoSystems Institute, University of California Los Angeles, Los Angeles, California.
| |
Collapse
|
23
|
Li Q, Lian T. Area- and Thickness-Dependent Biexciton Auger Recombination in Colloidal CdSe Nanoplatelets: Breaking the "Universal Volume Scaling Law". NANO LETTERS 2017; 17:3152-3158. [PMID: 28418671 DOI: 10.1021/acs.nanolett.7b00587] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Colloidal nanoplatelets (NPLs) have shown great potentials for lasing applications due to their sharp absorption and emission peaks, large absorption cross sections, large radiative decay rates, and long multiexciton lifetimes. How multiexciton lifetimes depend on material dimensions remains unknown in two-dimensional (2D) materials, despite being a key parameter affecting optical gain threshold and many other properties. Herein, we report a study of room-temperature biexciton Auger recombination time of CdSe NPLs as a function of thickness and lateral area. Comparison of all NPLs shows that the biexciton lifetime does not increase linearly with volume, unlike previously reported "universal volume scaling law" for quantum dots. For NPLs of the same thickness (∼1.8 nm), the biexciton lifetime increase linearly with their lateral area (from 143.7 ± 12.6 to 320.1 ± 17.1 ps when the area increases from 90.5 ± 21.4 to 234.2 ± 41.9 nm2). The biexciton lifetime depends linearly on (1/Ek(e))7/2 (Ek(e) is the electron confinement energy) or nearly linearly on d7 (d is NPL thickness). The observed dependence is consistent with a model in which biexciton Auger recombination rate scales with the product of exciton binary collision frequency and Auger recombination probability in biexciton complexes. The linear increase of Auger lifetimes with NPL lateral areas reflects a 1/area dependence of the binary collision frequency for 2D excitons and the thickness-dependent biexciton Auger recombination time is attributed to its strong dependence on the degree of quantum confinement. This model may be generally applicable to exciton Auger recombination in quantum confined 1D and 2D nanomaterials.
Collapse
Affiliation(s)
- Qiuyang Li
- Department of Chemistry, Emory University , 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University , 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| |
Collapse
|
24
|
Pietryga JM, Park YS, Lim J, Fidler AF, Bae WK, Brovelli S, Klimov VI. Spectroscopic and Device Aspects of Nanocrystal Quantum Dots. Chem Rev 2017; 116:10513-622. [PMID: 27677521 DOI: 10.1021/acs.chemrev.6b00169] [Citation(s) in RCA: 390] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The field of nanocrystal quantum dots (QDs) is already more than 30 years old, and yet continuing interest in these structures is driven by both the fascinating physics emerging from strong quantum confinement of electronic excitations, as well as a large number of prospective applications that could benefit from the tunable properties and amenability toward solution-based processing of these materials. The focus of this review is on recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion. A specific underlying theme is innovative concepts for tuning the properties of QDs beyond what is possible via traditional size manipulation, particularly through heterostructuring. Examples of such advanced control of nanocrystal functionalities include the following: interface engineering for suppressing Auger recombination in the context of QD LEDs and lasers; Stokes-shift engineering for applications in large-area luminescent solar concentrators; and control of intraband relaxation for enhanced carrier multiplication in advanced QD photovoltaics. We examine the considerable recent progress on these multiple fronts of nanocrystal research, which has resulted in the first commercialized QD technologies. These successes explain the continuing appeal of this field to a broad community of scientists and engineers, which in turn ensures even more exciting results to come from future exploration of this fascinating class of materials.
Collapse
Affiliation(s)
- Jeffrey M Pietryga
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Young-Shin Park
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.,Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Jaehoon Lim
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Andrew F Fidler
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Wan Ki Bae
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 02792, Korea
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , I-20125 Milano, Italy
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| |
Collapse
|
25
|
Zhang L, Liao C, Lv B, Wang X, Xiao M, Xu R, Yuan Y, Lu C, Cui Y, Zhang J. Single-Mode Lasing from "Giant" CdSe/CdS Core-Shell Quantum Dots in Distributed Feedback Structures. ACS APPLIED MATERIALS & INTERFACES 2017; 9:13293-13303. [PMID: 28357855 DOI: 10.1021/acsami.7b01669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
"Giant" semiconductor quantum dots (GQDs) have tremendous potential for applications in laser devices. Here, CdSe/CdS core-shell GQDs (11 monolayers) have been synthesized as lasing gain material. The photoluminescence decay of the GQD ensemble is single-exponential, and the two-photon absorption cross-section is above 105 GM. This article presents a versatile method for fabrication of CdSe/CdS GQD distributed feedback (DFB) lasers by laser interference ablation. A high-quality surface-relief grating structure can be readily created on the GQD thin films, and the relationship between laser beam intensity and surface modulation depth is studied. With appropriate periods, single-mode lasing emission has been detected from these devices under excitation wavelengths of 400 and 800 nm. The laser thresholds are as low as 0.028 and 1.03 mJ cm-2, with the lasing Q-factors of 709 and 586, respectively. Lasing operation is realized from the direct laser interference-ablated QD DFB structures for the first time.
Collapse
Affiliation(s)
- Lei Zhang
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Chen Liao
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Bihu Lv
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China
| | - Ruilin Xu
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Yufen Yuan
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Changgui Lu
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Yiping Cui
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| | - Jiayu Zhang
- Advanced Photonics Center, School of Electronic Science & Engineering, Southeast University , Nanjing 210096, China
| |
Collapse
|
26
|
Rabouw FT, de Mello Donega C. Excited-State Dynamics in Colloidal Semiconductor Nanocrystals. Top Curr Chem (Cham) 2016; 374:58. [PMID: 27573500 PMCID: PMC5480409 DOI: 10.1007/s41061-016-0060-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/23/2016] [Indexed: 11/29/2022]
Abstract
Colloidal semiconductor nanocrystals have attracted continuous worldwide interest over the last three decades owing to their remarkable and unique size- and shape-, dependent properties. The colloidal nature of these nanomaterials allows one to take full advantage of nanoscale effects to tailor their optoelectronic and physical–chemical properties, yielding materials that combine size-, shape-, and composition-dependent properties with easy surface manipulation and solution processing. These features have turned the study of colloidal semiconductor nanocrystals into a dynamic and multidisciplinary research field, with fascinating fundamental challenges and dazzling application prospects. This review focuses on the excited-state dynamics in these intriguing nanomaterials, covering a range of different relaxation mechanisms that span over 15 orders of magnitude, from a few femtoseconds to a few seconds after photoexcitation. In addition to reviewing the state of the art and highlighting the essential concepts in the field, we also discuss the relevance of the different relaxation processes to a number of potential applications, such as photovoltaics and LEDs. The fundamental physical and chemical principles needed to control and understand the properties of colloidal semiconductor nanocrystals are also addressed.
Collapse
Affiliation(s)
- Freddy T Rabouw
- Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.,Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.,Optical Materials Engineering Laboratory, ETH Zurich, 8092, Zurich, Switzerland
| | - Celso de Mello Donega
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA, Utrecht, The Netherlands.
| |
Collapse
|
27
|
Segarra C, Climente JI, Polovitsyn A, Rajadell F, Moreels I, Planelles J. Piezoelectric Control of the Exciton Wave Function in Colloidal CdSe/CdS Nanocrystals. J Phys Chem Lett 2016; 7:2182-2188. [PMID: 27225599 DOI: 10.1021/acs.jpclett.6b00622] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using multiband k·p calculations, we show that strain-engineered piezoelectricity is a powerful tool to modulate the electron-hole spatial separation in a wide class of wurtzite CdSe/CdS nanocrystals. The inherent anisotropy of the hexagonal crystal structure leads to anisotropic strain and, consequently, to a pronounced piezoelectric field along the c axis, which can be amplified or quenched through a proper design of the core-shell structure. The use of large cores and thick shells promotes a gradual departure from quantum confined nanocrystals to a regime dominated by piezoelectric confinement. This allows excitons to evolve from the usual type-I and quasi-type-II behavior to a type-II behavior in dot-in-dots, dot-in-rods, rod-in-rods, and dot-in-plates. Piezoelectric fields explain experimental observations for giant-shell nanocrystals, whose time-resolved photoluminescence reveals long exciton lifetimes for large cores, contrary to the expectations of standard quantum confinement models. They also explain the large differences in exciton lifetimes reported for different classes of CdSe/CdS nanocrystals.
Collapse
Affiliation(s)
- Carlos Segarra
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | | | - Fernando Rajadell
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Iwan Moreels
- Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| |
Collapse
|
28
|
Vaxenburg R, Rodina A, Lifshitz E, L Efros A. Biexciton Auger Recombination in CdSe/CdS Core/Shell Semiconductor Nanocrystals. NANO LETTERS 2016; 16:2503-11. [PMID: 26950398 DOI: 10.1021/acs.nanolett.6b00066] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A theoretical study of the positive and negative trion channels in the nonradiative Auger recombination of band-edge biexcitons (BXs) in CdSe/CdS core/shell nanocrystals (NCs) is presented. The theory takes into account the BX fine-structure produced by NC asymmetry and hole-hole exchange interaction. The calculations show that growth of CdS shell upon CdSe core suppresses the rate of the Auger recombination via negative trion channel, while the more efficient Auger recombination via positive trion channel shows much weaker dependence on the shell thickness. The demonstrated oscillatory dependence of the BX Auger rate on the core and shell sizes is explained qualitatively in terms of overlap of the ground and excited carrier wave functions. The calculations show that raise of temperature accelerates the Auger recombination in CdSe/CdS NCs due to reduction of the bulk energy gaps of CdSe and CdS.
Collapse
Affiliation(s)
- Roman Vaxenburg
- George Mason University , Fairfax, Virginia 22030, United States
| | - Anna Rodina
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
| | - Efrat Lifshitz
- Technion - Israel Institute of Technology , Haifa 32000, Israel
| | | |
Collapse
|
29
|
Beane GA, Gong K, Kelley DF. Auger and Carrier Trapping Dynamics in Core/Shell Quantum Dots Having Sharp and Alloyed Interfaces. ACS NANO 2016; 10:3755-3765. [PMID: 26895220 DOI: 10.1021/acsnano.6b00370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The role of interface sharpness in controlling the excited state dynamics in CdSe/ZnSe core/shell particles is examined here. Particles composed of CdSe/ZnSe with 2.4-4.0 nm diameter cores and approximately 4 monolayer shells are synthesized at relatively low temperature, ensuring a sharp core-shell interface. Subsequent annealing results in cadmium and zinc interdiffusion, softening the interface. TEM imaging and absorption spectra reveal that annealing results in no change in the particle sizes. Annealing results in a 5-10 nm blue shift in the absorption spectrum, which is compared to calculated spectral shifts to characterize the extent of metal interdiffusion. The one- and two-photon dynamics are measured using time-resolved absorption spectroscopy. We find that biexcitons undergo biexponential decays, with fast and slow decay times differing by about an order of magnitude. The relative magnitudes of the fast and slow components depend on the sharpness of the core-shell interface, with larger fast component amplitudes associated with a sharp core-shell interface. The slow component is assigned to Auger recombination of band edge carriers and the fast decay component to Auger recombination of holes that are trapped in defects produced by lattice strain. Annealing of these particles softens the core-shell interface and thereby reduces the amount of lattice strain and diminishes the magnitude of the fast decay component. The time constant of the slow biexciton Auger recombination component changes only slightly upon softening of the core-shell interface.
Collapse
Affiliation(s)
- Gary A Beane
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - Ke Gong
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| | - David F Kelley
- Chemistry and Chemical Biology, University of California Merced , 5200 North Lake Road, Merced, California 95343, United States
| |
Collapse
|
30
|
Park YS, Bae WK, Baker T, Lim J, Klimov VI. Effect of Auger Recombination on Lasing in Heterostructured Quantum Dots with Engineered Core/Shell Interfaces. NANO LETTERS 2015; 15:7319-28. [PMID: 26397312 DOI: 10.1021/acs.nanolett.5b02595] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nanocrystal quantum dots (QDs) are attractive materials for applications as laser media because of their bright, size-tunable emission and the flexibility afforded by colloidal synthesis. Nonradiative Auger recombination, however, hampers optical amplification in QDs by rapidly depleting the population of gain-active multiexciton states. In order to elucidate the role of Auger recombination in QD lasing and isolate its influence from other factors that might affect optical gain, we study two types of CdSe/CdS core/shell QDs with the same core radii and the same total sizes but different properties of the core/shell interface ("sharp" vs "smooth"). These samples exhibit distinctly different biexciton Auger lifetimes but are otherwise virtually identical. The suppression of Auger recombination in the sample with a smooth (alloyed) interface results in a notable improvement in the optical gain performance manifested in the reduction of the threshold for amplified spontaneous emission and the ability to produce dual-color lasing involving both the band-edge (1S) and the higher-energy (1P) electronic states. We develop a model, which explicitly accounts for the multiexciton nature of optical gain in QDs, and use it to analyze the competition between stimulated emission from multiexcitons and their decay via Auger recombination. These studies re-emphasize the importance of Auger recombination control for the realization of real-life QD-based lasing technologies and offer practical strategies for suppression of Auger recombination via "interface engineering" in core/shell structures.
Collapse
Affiliation(s)
- Young-Shin Park
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Wan Ki Bae
- Photo-Electronic Hybrids Research Center, National Agenda Research Division, Korea Institute of Science and Technology , Seoul 02792, Korea
| | - Thomas Baker
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Jaehoon Lim
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| |
Collapse
|
31
|
Grim JQ, Manna L, Moreels I. A sustainable future for photonic colloidal nanocrystals. Chem Soc Rev 2015; 44:5897-914. [PMID: 26084788 DOI: 10.1039/c5cs00285k] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Colloidal nanocrystals - produced in a growing variety of shapes, sizes and compositions - are rapidly developing into a new generation of photonic materials, spanning light emitting as well as energy harvesting applications. Precise tailoring of their optoelectronic properties enables them to satisfy disparate application-specific requirements. However, the presence of toxic heavy metals such as cadmium and lead in some of the most mature nanocrystals is a serious drawback which may ultimately preclude their use in consumer applications. Although the pursuit of non-toxic alternatives has occurred in parallel to the well-developed Cd- and Pb-based nanocrystals, synthetic challenges have, until recently, curbed progress. In this review, we highlight recent advances in the development of heavy-metal-free nanocrystals within the context of specific photonic applications. We also describe strategies to transfer some of the advantageous nanocrystal features such as shape control to non-toxic materials. Finally, we present recent developments that have the potential to make substantial impacts on the quest to attain a balance between performance and sustainability in photonics.
Collapse
Affiliation(s)
- Joel Q Grim
- Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, IT-16163 Genova, Italy.
| | | | | |
Collapse
|
32
|
Guzelturk B, Kelestemur Y, Gungor K, Yeltik A, Akgul MZ, Wang Y, Chen R, Dang C, Sun H, Demir HV. Stable and Low-Threshold Optical Gain in CdSe/CdS Quantum Dots: An All-Colloidal Frequency Up-Converted Laser. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:2741-6. [PMID: 25807924 DOI: 10.1002/adma.201500418] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 02/24/2015] [Indexed: 05/16/2023]
Abstract
An all-solution processed and all-colloidal laser is demonstrated using tailored CdSe/CdS core/shell quantum dots, which exhibit highly stable and low-threshold optical gain owing to substantially suppressed non-radiative Auger recombination.
Collapse
Affiliation(s)
- Burak Guzelturk
- Department of Electrical and Electronics Engineering, Department of Physics, and UNAM-National, Nanotechnology Research Center, Institute of Materials Science and Nanotechnology, Bilkent University, TR-06800, Bilkent, Ankara, Turkey
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Grim JQ, Christodoulou S, Di Stasio F, Krahne R, Cingolani R, Manna L, Moreels I. Continuous-wave biexciton lasing at room temperature using solution-processed quantum wells. NATURE NANOTECHNOLOGY 2014; 9:891-5. [PMID: 25282045 DOI: 10.1038/nnano.2014.213] [Citation(s) in RCA: 229] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 08/26/2014] [Indexed: 05/19/2023]
Abstract
Solution-processed inorganic and organic materials have been pursued for more than a decade as low-threshold, high-gain lasing media, motivated in large part by their tunable optoelectronic properties and ease of synthesis and processing. Although both have demonstrated stimulated emission and lasing, they have not yet approached the continuous-wave pumping regime. Two-dimensional CdSe colloidal nanosheets combine the advantage of solution synthesis with the optoelectronic properties of epitaxial two-dimensional quantum wells. Here, we show that these colloidal quantum wells possess large exciton and biexciton binding energies of 132 meV and 30 meV, respectively, giving rise to stimulated emission from biexcitons at room temperature. Under femtosecond pulsed excitation, close-packed thin films yield an ultralow stimulated emission threshold of 6 μJ cm(-2), sufficient to achieve continuous-wave pumped stimulated emission, and lasing when these layers are embedded in surface-emitting microcavities.
Collapse
Affiliation(s)
- Joel Q Grim
- Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy
| | | | | | - Roman Krahne
- Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy
| | - Roberto Cingolani
- Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy
| | - Liberato Manna
- Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy
| | - Iwan Moreels
- Istituto Italiano di Tecnologia, via Morego 30, IT-16163 Genova, Italy
| |
Collapse
|
34
|
Controlling the influence of Auger recombination on the performance of quantum-dot light-emitting diodes. Nat Commun 2014; 4:2661. [PMID: 24157692 PMCID: PMC3826634 DOI: 10.1038/ncomms3661] [Citation(s) in RCA: 286] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 09/23/2013] [Indexed: 11/08/2022] Open
Abstract
Development of light-emitting diodes (LEDs) based on colloidal quantum dots is driven by attractive properties of these fluorophores such as spectrally narrow, tunable emission and facile processibility via solution-based methods. A current obstacle towards improved LED performance is an incomplete understanding of the roles of extrinsic factors, such as non-radiative recombination at surface defects, versus intrinsic processes, such as multicarrier Auger recombination or electron-hole separation due to applied electric field. Here we address this problem with studies that correlate the excited state dynamics of structurally engineered quantum dots with their emissive performance within LEDs. We find that because of significant charging of quantum dots with extra electrons, Auger recombination greatly impacts both LED efficiency and the onset of efficiency roll-off at high currents. Further, we demonstrate two specific approaches for mitigating this problem using heterostructured quantum dots, either by suppressing Auger decay through the introduction of an intermediate alloyed layer, or by using an additional shell that impedes electron transfer into the quantum dot to help balance electron and hole injection. Auger recombination is a loss process that considerably reduces the efficiency of many quantum-dot light-emitting diodes. Here the authors demonstrate that designs such as heterostructure quantum dots can considerably suppress Auger decay in light-emitting diodes.
Collapse
|
35
|
Park YS, Bae WK, Padilha LA, Pietryga JM, Klimov VI. Effect of the core/shell interface on auger recombination evaluated by single-quantum-dot spectroscopy. NANO LETTERS 2014; 14:396-402. [PMID: 24397307 DOI: 10.1021/nl403289w] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Previous single-particle spectroscopic studies of colloidal quantum dots have indicated a significant spread in biexciton lifetimes across an ensemble of nominally identical nanocrystals. It has been speculated that in addition to dot-to-dot variation in physical dimensions, this spread is contributed to by variations in the structure of the quantum dot interface, which controls the shape of the confinement potential. Here, we directly evaluate the effect of the composition of the core-shell interface on single- and multiexciton dynamics via side-by-side measurements of individual core-shell CdSe/CdS nanocrystals with a sharp versus smooth (graded) interface. To realize the latter type of structures we incorporate a CdSexS1-x alloy layer of controlled composition and thickness between the CdSe core and the CdS shell. We observe that while having essentially no effect on single-exciton decay, the interfacial alloy layer leads to a systematic increase in biexciton lifetimes, which correlates with the increase in the biexciton emission efficiency, as inferred from two-photon correlation measurements. These observations provide direct experimental evidence that in addition to the size of the quantum dot, its interfacial properties also significantly affect the rate of Auger recombination, which governs biexciton decay. These findings help rationalize previous observations of a significant heterogeneity in the biexciton lifetimes across similarly sized quantum dots and should facilitate the development of "Auger-recombination-free" colloidal nanostructures for a range of applications from lasers and light-emitting diodes to photodetectors and solar cells.
Collapse
Affiliation(s)
- Young-Shin Park
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | | | | | | | | |
Collapse
|
36
|
Xu W, Ji W, Jing P, Yuan X, Wang YA, Xiang W, Zhao J. Efficient inverted quantum-dot light-emitting devices with TiO2/ZnO bilayer as the electron contact layer. OPTICS LETTERS 2014; 39:426-429. [PMID: 24487831 DOI: 10.1364/ol.39.000426] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We have demonstrated an efficient inverted CdSe/CdS/ZnS core/shell quantum-dot light-emitting device (QD-LED) using a solution-processed sol-gel TiO2 and ZnO nanoparticle composite layer as an electron-injection layer with controllable morphology and investigated the electroluminescence mechanism. The introduction of the ZnO layer can lead to the formation of spin-coated uniform QD films and fabrication of high-luminance QD-LEDs. The TiO2 layer improves the balance of charge injection due to its lower electron mobility relative to the ZnO layer. These results offer a practicable platform for the realization of a trade-off between the luminance and efficiency in the inverted QD-LEDs with TiO2/ZnO composites as the electron contact layer.
Collapse
|
37
|
|
38
|
Rabouw FT, Lunnemann P, van Dijk-Moes RJA, Frimmer M, Pietra F, Koenderink AF, Vanmaekelbergh D. Reduced Auger recombination in single CdSe/CdS nanorods by one-dimensional electron delocalization. NANO LETTERS 2013; 13:4884-92. [PMID: 24010869 DOI: 10.1021/nl4027567] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Progress to reduce nonradiative Auger decay in colloidal nanocrystals has recently been made by growing thick shells. However, the physics of Auger suppression is not yet fully understood. Here, we examine the dynamics and spectral characteristics of single CdSe-dot-in-CdS-rod nanocrystals. These exhibit blinking due to charging/discharging, as well as trap-related blinking. We show that one-dimensional electron delocalization into the rod-shaped shell can be as effective as a thick spherical shell at reducing Auger recombination of the negative trion state.
Collapse
Affiliation(s)
- Freddy T Rabouw
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science , Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
39
|
Bae WK, Padilha LA, Park YS, McDaniel H, Robel I, Pietryga JM, Klimov VI. Controlled alloying of the core-shell interface in CdSe/CdS quantum dots for suppression of Auger recombination. ACS NANO 2013; 7:3411-9. [PMID: 23521208 DOI: 10.1021/nn4002825] [Citation(s) in RCA: 221] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The influence of a CdSexS1-x interfacial alloyed layer on the photophysical properties of core/shell CdSe/CdS nanocrystal quantum dots (QDs) is investigated by comparing reference QDs with a sharp core/shell interface to alloyed structures with an intermediate CdSexS1-x layer at the core/shell interface. To fully realize the structural contrast, we have developed two novel synthetic approaches: a method for fast CdS-shell growth, which results in an abrupt core/shell boundary (no intentional or unintentional alloying), and a method for depositing a CdSexS1-x alloy layer of controlled composition onto the CdSe core prior to the growth of the CdS shell. Both types of QDs possess similar size-dependent single-exciton properties (photoluminescence energy, quantum yield, and decay lifetime). However the alloyed QDs show a significantly longer biexciton lifetime and up to a 3-fold increase in the biexciton emission efficiency compared to the reference samples. These results provide direct evidence that the structure of the QD interface has a significant effect on the rate of nonradiative Auger recombination, which dominates biexciton decay. We also observe that the energy gradient at the core-shell interface introduced by the alloyed layer accelerates hole trapping from the shell to the core states, which results in suppression of shell emission. This comparative study offers practical guidelines for controlling multicarrier Auger recombination without a significant effect on either spectral or dynamical properties of single excitons. The proposed strategy should be applicable to QDs of a variety of compositions (including, e.g., infrared-emitting QDs) and can benefit numerous applications from light emitting diodes and lasers to photodetectors and photovoltaics.
Collapse
Affiliation(s)
- Wan Ki Bae
- Center for Advanced Solar Photophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | | | | | | | | | | | | |
Collapse
|
40
|
Shafran E, Borys NJ, Huang J, Talapin DV, Lupton JM. Indirect Exciton Formation due to Inhibited Carrier Thermalization in Single CdSe/CdS Nanocrystals. J Phys Chem Lett 2013; 4:691-697. [PMID: 26281888 DOI: 10.1021/jz400070g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Temperature-dependent single-particle spectroscopy is used to study interfacial energy transfer in model light-harvesting CdSe/CdS core-shell tetrapod nanocrystals. Using alternating excitation energies, we identify two thermalized exciton states in single nanoparticles that are attributed to a strain-induced interfacial barrier. At cryogenic temperatures, emission from both states exemplifies the effects of intraparticle disorder and enables their simultaneous characterization, revealing that the two states are distinct in regards to emission polarization, spectral diffusion, and blinking.
Collapse
Affiliation(s)
| | | | - Jing Huang
- ‡Department of Chemistry, The University of Chicago, Chicago, Illinois 610637, United States
| | - Dmitri V Talapin
- ‡Department of Chemistry, The University of Chicago, Chicago, Illinois 610637, United States
| | - John M Lupton
- §Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93053 Regensburg, Germany
| |
Collapse
|