1
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Mondal AK, Pan X, Kwon O, Vardeny ZV. Degradation Analysis of Organic Light-Emitting Diodes through Dispersive Magneto-Electroluminescence Response. ACS APPLIED MATERIALS & INTERFACES 2023; 15:9697-9704. [PMID: 36749918 DOI: 10.1021/acsami.2c20070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Understanding the stability and degradation of organic light-emitting diodes (OLEDs) under working conditions is a significant area of research for developing more effective OLEDs and further improving their performance. However, studies of degradation processes by in situ noninvasive methods have not been adequately developed. In this work, tris-(8-hydroxyquinolino) aluminum (Alq3)-based OLED degradation processes have been analyzed through the investigation of the device dispersive magneto-electroluminescence (MEL(B)) response measured at room temperature. By studying the change in the MEL(B) response during the device degradation under different external stimuli, such as exposing the device to the atmosphere and prolonged illumination by a strong visible light source, we have gained insight into the microscopic spin-dependent phenomena that control the recombination of e-h polaron pairs in the device. We found that the device degradation leads to a shorter e-h polaron lifetime, smaller dispersive parameter, and broader lifetime distribution function that shows increased disorder in the active layer. This study could offer a potential tool that may be beneficial for assessing the degradation of OLED devices based on various active layers.
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Affiliation(s)
- Amit Kumar Mondal
- Department of Physics & Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Xin Pan
- Department of Physics & Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
| | - Ohyun Kwon
- Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., 130, Samsung-Ro, Yeongtong-gu, Suwon-Si 16678, Gyeonggi-do, Republic of Korea
| | - Zeev Valy Vardeny
- Department of Physics & Astronomy, University of Utah, Salt Lake City, Utah 84112, United States
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2
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Ohta K, Tominaga K, Ikoma T, Kobori Y, Yamada H. Microscopic Structures, Dynamics, and Spin Configuration of the Charge Carriers in Organic Photovoltaic Solar Cells Studied by Advanced Time-Resolved Spectroscopic Methods. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7365-7382. [PMID: 35675205 DOI: 10.1021/acs.langmuir.2c00290] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Organic photovoltaics (OPVs) are promising solutions for renewable energy and sustainable technologies and have attracted much attention in recent years. Two types of organic semiconductors are used as donor materials to fabricate OPV cells. One type is a photoconductive polymer, and the other type is a small-molecule-based compound. The discovery of a bulk-heterojunction (BHJ) structure using a mixture of p- and n-type organic semiconductors has dramatically increased the power conversion efficiency (PCE) of OPV cells. In this feature article, we review our recent studies on organic BHJ thin films and OPVs by using advanced time-resolved spectroscopic techniques. Two topics regarding the microscopic behaviors of the charge carriers are discussed. The first topic is focused on how to quantify the local mobility of the charge carriers. Here, we discuss charge carrier dynamics in diketopyrrolopyrrole-linked tetrabenzoporphyrin (DPP-BP) BHJ thin films studied by time-resolved terahertz spectroscopy on a subpicosecond to several tens of picoseconds time scale and by transient photocurrent measurements on a microsecond time scale. The second topic concerns the spin configuration and interaction of the electron and hole of the polaron pairs in polymer-based BHJ thin films and OPV cells studied by the time-resolved electron paramagnetic resonance method, time-resolved simultaneous optical and electrical detection, and measurement of the magnetoconductance effect.
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Affiliation(s)
- Kaoru Ohta
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Keisuke Tominaga
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Tadaaki Ikoma
- Graduate School of Science and Technology, Niigata University, 2-8050, Ikarashi, Nishi-ku, Niigata950-2181, Japan
| | - Yasuhiro Kobori
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Hiroko Yamada
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5, Takayama-cho, Ikoma, Nara630-0192, Japan
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3
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Zhukov I, Fishman N, Kiryutin A, Lukzen N, Steiner UE, Vieth HM, Schäfer J, Lambert C, Yurkovskaya A. Mapping 13C hyperfine couplings and exchange interactions in short-lived charge separated states of rigid donor-bridge-acceptor dyads. J Chem Phys 2021; 155:224201. [PMID: 34911300 DOI: 10.1063/5.0073193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A detailed experimental study on reversible photo-induced intramolecular charge separation is presented based on nuclear magnetic resonance detection of chemically induced dynamic nuclear polarization. From variation of such polarization with the external magnetic field, the coupling constants of isotropic and anisotropic hyperfine interactions at individual 13C sites are measured in the short-lived charge separated state of dyad molecules composed of donor-bridge-acceptor parts. The objects of study were rigid donor-bridge-acceptor dyads, consisting of triarylamine as a donor, naphthalene diimide as an acceptor, and a meta-conjugated diethynylbenzene fragment as a bridge. By systematic variation of side groups in the bridging moiety, their influence on the electron withdrawing strength is traced. In combination with similar data for the 1H positions obtained previously for the same compounds [I. Zhukov et al., J. Chem. Phys. 152, 014203 (2020)], our results provide a reliable basis for the determination of the spin density distribution in the charge separated state of such dyads.
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Affiliation(s)
- Ivan Zhukov
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
| | - Natalya Fishman
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
| | - Alexey Kiryutin
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
| | - Nikita Lukzen
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
| | - Ulrich E Steiner
- Department of Chemistry, University of Konstanz, Universitätsstraße 14, 78457 Konstanz, Germany
| | - Hans-Martin Vieth
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
| | - Julian Schäfer
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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4
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Nikiforov D, Ehrenfreund E. Magnetic Field Effects of Charge Transfer Excitons in Organic Semiconductor Devices. Isr J Chem 2021. [DOI: 10.1002/ijch.202100091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Daniel Nikiforov
- Physics Department and Solid State Institute Technion-Israel Institute of Technology Haifa 3200003 Israel
| | - Eitan Ehrenfreund
- Physics Department and Solid State Institute Technion-Israel Institute of Technology Haifa 3200003 Israel
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5
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Wang Z, Liu H, Xie X, Zhang C, Wang R, Chen L, Xu Y, Ma H, Fang W, Yao Y, Sang H, Wang X, Li X, Xiao M. Free-triplet generation with improved efficiency in tetracene oligomers through spatially separated triplet pair states. Nat Chem 2021; 13:559-567. [PMID: 33833447 DOI: 10.1038/s41557-021-00665-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 02/22/2021] [Indexed: 02/01/2023]
Abstract
Singlet fission (SF) can potentially boost the efficiency of solar energy conversion by converting a singlet exciton (S1) into two free triplets (T1 + T1) through an intermediate state of a correlated triplet pair (TT). Although efficient TT generation has been recently realized in many intramolecular SF materials, their potential applications have been hindered by the poor efficiency of TT dissociation. Here we demonstrate that this can be overcome by employing a spatially separated 1(T…T) state with weak intertriplet coupling in tetracene oligomers with three or more chromophores. By using transient magneto-optical spectroscopic methods, we show that free-triplet generation can be markedly enhanced through the SF pathway that involves the spatially separated 1(T…T) state rather than the pathway mediated by the spatially adjacent TT state, leading to a marked improvement in free-triplet generation with an efficiency increase from 21% for the dimer to 85% (124%) for the trimer (tetramer).
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Affiliation(s)
- Zhiwei Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Heyuan Liu
- School of Materials Science and Engineering, Institute of New Energy, China University of Petroleum (East China), Qingdao, China
| | - Xiaoyu Xie
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
| | - Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Lan Chen
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Yihe Xu
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China
| | - Haibo Ma
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China.
| | - Weihai Fang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China.,Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education, Department of Chemistry, Beijing Normal University, Beijing, China
| | - Yao Yao
- Department of Physics and State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, China
| | - Hai Sang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xiyou Li
- School of Materials Science and Engineering, Institute of New Energy, China University of Petroleum (East China), Qingdao, China.
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China. .,Department of Physics, University of Arkansas, Fayetteville, AR, USA.
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6
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Kim T, Kim J, Ke XS, Brewster JT, Oh J, Sessler JL, Kim D. Magnetic-Field-Induced Modulation of Charge-Recombination Dynamics in a Rosarin-Fullerene Complex. Angew Chem Int Ed Engl 2021; 60:9379-9383. [PMID: 33590640 DOI: 10.1002/anie.202017332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Indexed: 11/10/2022]
Abstract
Charge-recombination processes are critical for photovoltaic applications and should be suppressed for efficient charge transport. Here, we report that an applied magnetic field (0-1 T) can be used control the charge-recombination dynamics in an expanded rosarin-C60 complex. In the low magnetic field regime (<100 mT), the charge-recombination rate slows down due to hyperfine coupling, as inferred from transient absorption spectroscopic analyses. In contrast, in the high field regime, i.e., over 500 mT, the charge-recombination rate recovers and increases because the Δg mechanism facilitates spin conversion to a triplet charge-separated state (S to T0 ) that undergoes rapid charge-recombination to a localized rosarin triplet state. Therefore, we highlight the charge-recombination rate and the localized triplet state population can be modulated by the magnetic field in charge donor/acceptor non-covalent complexes.
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Affiliation(s)
- Taeyeon Kim
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea.,Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois, 60208-3113, United States
| | - Juno Kim
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
| | - Xian-Sheng Ke
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712-1224, USA
| | - James T Brewster
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712-1224, USA
| | - Juwon Oh
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea.,Department of Chemistry, Soonchunhyang University, Chungnam, 31538, Republic of Korea
| | - Jonathan L Sessler
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712-1224, USA
| | - Dongho Kim
- Department of Chemistry, Spectroscopy Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Republic of Korea
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7
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Kim T, Kim J, Ke X, Brewster JT, Oh J, Sessler JL, Kim D. Magnetic‐Field‐Induced Modulation of Charge‐Recombination Dynamics in a Rosarin‐Fullerene Complex. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202017332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Taeyeon Kim
- Department of Chemistry Spectroscopy Laboratory for Functional π-Electronic Systems Yonsei University Seoul 03722 Republic of Korea
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern Northwestern University Evanston, Illinois 60208-3113 United States
| | - Juno Kim
- Department of Chemistry Spectroscopy Laboratory for Functional π-Electronic Systems Yonsei University Seoul 03722 Republic of Korea
| | - Xian‐Sheng Ke
- Department of Chemistry The University of Texas at Austin Austin TX 78712-1224 USA
| | - James T. Brewster
- Department of Chemistry The University of Texas at Austin Austin TX 78712-1224 USA
| | - Juwon Oh
- Department of Chemistry Spectroscopy Laboratory for Functional π-Electronic Systems Yonsei University Seoul 03722 Republic of Korea
- Department of Chemistry Soonchunhyang University Chungnam 31538 Republic of Korea
| | - Jonathan L. Sessler
- Department of Chemistry The University of Texas at Austin Austin TX 78712-1224 USA
| | - Dongho Kim
- Department of Chemistry Spectroscopy Laboratory for Functional π-Electronic Systems Yonsei University Seoul 03722 Republic of Korea
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8
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Abstract
At low temperatures and high magnetic fields, electron and hole spins in an organic light-emitting diode become polarized so that recombination preferentially forms molecular triplet excited-state species. For low device currents, magnetoelectroluminescence perfectly follows Boltzmann activation, implying a virtually complete polarization outcome. As the current increases, the magnetoelectroluminescence effect is reduced because spin polarization is suppressed by the reduction in carrier residence time within the device. Under these conditions, an additional field-dependent process affecting the spin-dependent recombination emerges, possibly related to the build-up of triplet excitons and their interaction with free charge carriers. Suppression of the EL alone does not prove electronic spin polarization. We therefore probe changes in the spin statistics of recombination directly in a dual singlet-triplet emitting material, which shows a concomitant rise in phosphorescence intensity as fluorescence is suppressed. Finite spin-orbit coupling in these materials gives rise to a microscopic distribution in effective g-factors of electrons and holes, Δg, i.e., a distribution in Larmor frequencies. This Δg effect in the pair, which mixes singlet and triplet, further suppresses singlet-exciton formation at high fields in addition to thermal spin polarization of the individual carriers. Though literature reports magnetoelectroluminescence (MEL) affects in organic light‐emitting diodes (OLEDs), probing the organic layer’s effective spin polarization remains a challenge. Here, the authors utilize dual singlet‐triplet emitting OLEDs to reveal the spin polarization in the materials.
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9
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Pham MT, Amerling E, Luong HM, Pham HT, Larsen GK, Whittaker-Brooks L, Nguyen TD. Origin of Rashba Spin-Orbit Coupling in 2D and 3D Lead Iodide Perovskites. Sci Rep 2020; 10:4964. [PMID: 32188917 PMCID: PMC7080819 DOI: 10.1038/s41598-020-61768-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/03/2020] [Indexed: 11/09/2022] Open
Abstract
We studied spin dynamics of charge carriers in the superlattice-like Ruddlesden-Popper hybrid lead iodide perovskite semiconductors, 2D (BA)2(MA)Pb2I7 (with MA = CH3NH3, and BA = CH3(CH2)3NH3), and 3D MAPbI3 using the magnetic field effect (MFE) on conductivity and electroluminescence in their light emitting diodes (LEDs) at cryogenic temperatures. The semiconductors with distinct structural/bulk inversion symmetry breaking, when combined with colossal intrinsic spin-orbit coupling (SOC), theoretically give rise to giant Rashba-type SOC. We found that the magneto-conductance (MC) magnitude increases monotonically with the emission intensity and saturates at ≈0.05% and 0.11% for the MAPbI3 and (BA)2(MA)Pb2I7, respectively. The magneto-electroluminescence (MEL) response with similar line shapes as the MC response has a significantly larger magnitude, and essentially stays constant at ≈0.22% and ≈0.20% for MAPbI3 and (BA)2(MA)Pb2I7, respectively. The sign and magnitude of the MC and MEL responses can be quantitatively explained in the framework of the Δg-based excitonic model using rate equations. Remarkably, the width of the MEL response in those materials linearly increases with increasing the applied electric field, where the Rashba coefficient in (BA)2(MA)Pb2I7 is estimated to be about 7 times larger than that in MAPbI3. Our studies might have significant impact on future development of electrically-controlled spin logic devices via Rashba-like effects.
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Affiliation(s)
- Minh T Pham
- Department of Physics & Astronomy, University of Georgia, Athens, GA, 30602, USA
| | - Eric Amerling
- Department of Chemistry, University of Utah, Salt Lake City, UT, 84112, USA
| | - Hoang M Luong
- Department of Physics & Astronomy, University of Georgia, Athens, GA, 30602, USA
| | - Huy T Pham
- Department of Materials Science and Engineering, Phenikaa University, Ha Dong, Hanoi, 10000, Vietnam
| | - George K Larsen
- National Security Directorate, Savannah River National Laboratory, Aiken, South Carolina, 29808, USA
| | | | - Tho D Nguyen
- Department of Physics & Astronomy, University of Georgia, Athens, GA, 30602, USA.
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10
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Bairagi K, Romero DG, Calavalle F, Catalano S, Zuccatti E, Llopis R, Casanova F, Hueso LE. Room-Temperature Operation of a p-Type Molecular Spin Photovoltaic Device on a Transparent Substrate. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906908. [PMID: 31944432 DOI: 10.1002/adma.201906908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/19/2019] [Indexed: 06/10/2023]
Abstract
The coupling of diverse degrees of freedom opens the door to physical effects that go beyond each of them individually, making multifunctionality a much sought-after attribute for high-performance devices. Here, the multifunctional operation of a single-layer p-type organic device, displaying both spin transport and photovoltaic effect at the room temperature on a transparent substrate, is shown. The generated photovoltage is almost three times larger than the applied bias to the device which facilitates the modulation of the magnetic response of the device with both bias and light. The device shows an increase in power conversion efficiency under magnetic field, an ability to invert the current with magnetic field and under certain conditions it can act as a spin photodetector with zero power consumption in the standby mode. The room-temperature exploitation of the interplay among light, bias, and magnetic field in the single device with a p-type molecule opens a way toward the development of efficient high-performance spin photovoltaic cells.
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Affiliation(s)
- Kaushik Bairagi
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain
| | | | | | - Sara Catalano
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain
| | | | - Roger Llopis
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain
| | - Fèlix Casanova
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Basque Country, Spain
| | - Luis E Hueso
- CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain
- IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Basque Country, Spain
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11
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Pan X, Liu H, Huynh U, Vardeny ZV. Magneto-electroluminescence response in 2D and 3D hybrid organic–inorganic perovskite light emitting diodes. J Chem Phys 2020; 152:044714. [DOI: 10.1063/1.5132982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Xin Pan
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Haoliang Liu
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Uyen Huynh
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - Z. Valy Vardeny
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
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12
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Nikiforov D, Khachatryan B, Tessler N, Ehrenfreund E. Effects of fast back-fusion of charge transfer excimers on magneto-photocurrent in organic light emitting diodes. J Chem Phys 2020; 152:034707. [PMID: 31968974 DOI: 10.1063/1.5131481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We report the magnetic field dependence of the magneto-photocurrent (MPC) in organic light emitting diodes made of homo-polymer organic layers and compare it to the measured magneto-conductance (MC) in the same diodes. We find that the response MPC(B) is very different from MC(B) in at least two respects. (a) The low field (B < 50 mT) response of MPC(B) is narrower by a factor of ∼5 from that of MC(B). (b) At high fields (B > 4 T), MPC(B) has a stronger dependence on B, d(MPC)/dB ∼ 5d(MC)/dB. We attribute these differences to a unique feature of charge transfer excimers that are responsible for MPC: sub-ns fast fusion back to singlet excitons and slow (ns to μs) dissociation to free charges. In contrast, MC(B) is determined by long lived (>10 ns) polaron pairs having singlet and triplet dissociation rates of the same order.
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Affiliation(s)
- D Nikiforov
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - B Khachatryan
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - N Tessler
- Department of Electrical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - E Ehrenfreund
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
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13
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Zhukov I, Fishman N, Kiryutin A, Lukzen N, Panov M, Steiner U, Vieth HM, Schäfer J, Lambert C, Yurkovskaya A. Positive electronic exchange interaction and predominance of minor triplet channel in CIDNP formation in short lived charge separated states of D-X-A dyads. J Chem Phys 2020; 152:014203. [DOI: 10.1063/1.5131817] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ivan Zhukov
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Natalya Fishman
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Alexey Kiryutin
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Nikita Lukzen
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Mikhail Panov
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Ulrich Steiner
- Department of Chemistry, University of Konstanz, Universitätsstraße 14, 78457 Konstanz, Germany
| | - Hans-Martin Vieth
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Julian Schäfer
- Center for Nanosystems Chemistry, Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Center for Nanosystems Chemistry, Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Alexandra Yurkovskaya
- International Tomography Center, Institutskaya 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
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14
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Liu X, Chanana A, Liu H, Wang J, Kwon O, Choi B, Kim S, Vardeny ZV. Magneto-Electroluminescence Study of Fringe Field in "Magnetic" Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:30072-30078. [PMID: 31339685 DOI: 10.1021/acsami.9b07512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Magneto-electroluminescence (MEL) represents the electroluminescence intensity change upon application of an external magnetic field. We show that the MEL field response in "magnetic" organic light-emitting diodes, where one electrode is ferromagnetic (FM), is a powerful technique for measuring the induced fringe field, B⃗F, from the FM electrode in the organic layer. We found that the in-plane fringe field, B⃗F∥, from 3 nm Co and Ni80Fe20 FM electrodes is proportional to the applied field, B⃗∥. The fringe field of the 3 nm Ni80Fe20 film was also investigated for an applied out-of-plane magnetic field, B⃗⊥. We found that the out-of-plane fringe field has two components: a component that is parallel or antiparallel to B⃗⊥ and remains unchanged with the distance, d, from the FM electrode and the other component that is highly inhomogeneous, parallel to the surface, and steeply decreases with d. We show that the obtained B⃗F is independent of the underlying mechanism for the MEL(B) response and thus may be considered universal.
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Affiliation(s)
| | | | | | | | - Ohyun Kwon
- Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd. , 130, Samsung-Ro , Youngtong-Gu, Suwon-Si 16678 , Republic of Korea
| | - Byoungki Choi
- Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd. , 130, Samsung-Ro , Youngtong-Gu, Suwon-Si 16678 , Republic of Korea
| | - Sunghan Kim
- Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd. , 130, Samsung-Ro , Youngtong-Gu, Suwon-Si 16678 , Republic of Korea
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15
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Hu Y, Tang X, Pan R, Deng J, Zhu H, Xiong Z. Spin-pair state-induced exceptional magnetic field responses from a thermally activated delayed fluorescence-assisted fluorescent material doping system. Phys Chem Chem Phys 2019; 21:17673-17686. [PMID: 31364625 DOI: 10.1039/c9cp01201j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thermally activated delayed fluorescence (TADF) material 2,3,5,6-tetrakis(3,6-diphenylcarbazol-9-yl)-1,4-dicyanobenzene (4CzTPN-Ph) and the conventional fluorescent dopant 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) were used to co-dope the host material 4,4'-bis(carbazol-9-yl)biphenyl (CBP) for the fabrication of TADF-assisted fluorescent organic light-emitting diodes (OLEDs). Some exceptional magnetic field effect (MFE) curves with abundant structures and four tunable components within a low magnetic field range (≤50 mT) were obtained, in sharp contrast to the maximum of two components observed in typical OLEDs. These MFE components were easily tuned by the injection current, dopant concentration, working temperature, and dopant energy gap, leading to a wide variety of MFE curve line shapes. The experimental results are attributed to the spin-pair state inter-conversions occurring in the device, including intersystem crossing (ISC) of CBP polaron pairs, ISC of 4CzTPN-Ph polaron pairs, reverse ISC (RISC) of 4CzTPN-Ph excitons, RISC of DCJTB polaron pairs, DCJTB triplet fusion, and DCJTB triplet-charge annihilation. Moreover, the exciton energy transfer processes among the host material and the guest dopants had a pronounced impact on the formation of these four components. This work gives a deeper understanding of the microscopic mechanisms of TADF-based co-doped systems for the further development of organic magnetic field effects in the extensive field of OLEDs.
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Affiliation(s)
- Yeqian Hu
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, People's Republic of China.
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16
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Shoji R, Omori T, Wakikawa Y, Miura T, Ikoma T. Magnetoconductance Study on Nongeminate Recombination in Solar Cell Using Poly(3-hexylthiophene) and [6,6]-Phenyl-C 61-butyric Acid Methyl Ester. ACS OMEGA 2018; 3:9369-9377. [PMID: 31459070 PMCID: PMC6645052 DOI: 10.1021/acsomega.8b01746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 08/01/2018] [Indexed: 06/10/2023]
Abstract
The magnetoconductance (MC) effect was investigated for two types of organic solar cells with single junction (SJ) and bulk junction (BJ) of poly(3-hexylthiophene) (P3HT) as donor (D) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as acceptor (A). Three components with different half-field-at-half-maximums (B 1/2) of 4 ± 1, 20 ± 15 and >400 mT, hereafter referred to MCS,M,B in a sequence, were observed in the magnetic field dependence of the MC effects measured under dark and light conditions. The magnitude of the MCS,M,B components is sensitive to not only the junction structure of the cell but also the presence or absence of incident light. The bias voltage (V) dependence of the MC effect in the dark for the SJ-cell is maximized around the turn-on voltage (V ON) of the dark current, where a flat band condition of the active layer is achieved. The B 1/2 for the MCM component of the SJ-cell increases with V beyond V ON. In light, the BJ-cell exhibits the MC effect, whereas no effect is detected for the SJ-cell. The MCS,M components for the BJ-cell in light increase with the incident light power. The transient MCS,M components for the BJ-cell measured using a nanosecond pulse laser increases with the delay time after the flash. By integrating these phenomena and the phase of the MC effect, it is concluded that all of the MC components arise from the magnetic field effect on the spin conversion of nongeminate electron (e)-hole (h) pairs with spin-dependent charge recombinations at the D/A-interface. The B 1/2 values for MCS,M,B are, respectively, understood by the spin conversion due to the hyperfine interaction, the spin relaxation, and the g-factor difference for e (PCBM-) and h (P3HT+). Kinetic simulations of the MCS,M components for the BJ-cell observed at the short-circuit condition in light yield an efficiency of ca. 40% for the nongeminate recombination, which is accompanied by the generation of triplet excitons as well as relaxation to a ground singlet state. The loss mechanism of moderate triplet recombination suggests an important possibility to improve the power conversion efficiency by harvesting of the triplet excitons.
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Affiliation(s)
- Ryota Shoji
- Graduate
School of Science and Technology and Center for Coordination of Research
Facilities, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan
| | - Takuya Omori
- Graduate
School of Science and Technology and Center for Coordination of Research
Facilities, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan
| | - Yusuke Wakikawa
- Advanced
Instrumental Analysis Center, Shizuoka Institute
of Science and Technology, 2200-2 Toyosawa, Fukuroi, Shizuoka 437-8555, Japan
| | - Tomoaki Miura
- Graduate
School of Science and Technology and Center for Coordination of Research
Facilities, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan
| | - Tadaaki Ikoma
- Graduate
School of Science and Technology and Center for Coordination of Research
Facilities, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan
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17
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Huynh UNV, Basel TP, Ehrenfreund E, Vardeny ZV. Transient Magnetic Field Effect of Photoexcitations in Donor-Acceptor Organic Semiconductors. J Phys Chem Lett 2018; 9:4544-4549. [PMID: 30052444 DOI: 10.1021/acs.jpclett.8b01869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report transient photoinduced absorption (t-PA) and magnetic field ( B)-dependent t-PA (t-MPA( B)) in a pristine low band gap π-conjugated copolymer composed of donor and acceptor moieties, namely, the poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thi-eno[3,4- b]thiophenediyl]]) (or PTB7) used in photovoltaic applications. Unlike traditional π-conjugated polymers in which the primary photoexcitations are singlet excitons (SE), in pristine PTB7 we find at short times coexistence of two primary photoexcitation species, namely, SE and triplet-triplet (TT) pair. Both species are photogenerated directly from the ground state and are spin-correlated. Although the TT pair decomposes into two separate triplet excitons (TEs) in ∼100 ps, the separated TE spins are still entangled up to ∼6 μs. At longer times, the t-MPA( B) response of the surviving TEs shows transient narrowing effect, which is attributed to a distribution of the TE size.
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Affiliation(s)
- Uyen N V Huynh
- Physics and Astronomy Department , University of Utah , Salt Lake City , Utah 84112 , United States
| | - Tek P Basel
- Physics and Astronomy Department , University of Utah , Salt Lake City , Utah 84112 , United States
| | - Eitan Ehrenfreund
- Physics Department , Technion Institute of Technology , Haifa 32000 , Israel
| | - Zeev V Vardeny
- Physics and Astronomy Department , University of Utah , Salt Lake City , Utah 84112 , United States
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18
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Site-selective measurement of coupled spin pairs in an organic semiconductor. Proc Natl Acad Sci U S A 2018; 115:5077-5082. [PMID: 29720443 DOI: 10.1073/pnas.1718868115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
From organic electronics to biological systems, understanding the role of intermolecular interactions between spin pairs is a key challenge. Here we show how such pairs can be selectively addressed with combined spin and optical sensitivity. We demonstrate this for bound pairs of spin-triplet excitations formed by singlet fission, with direct applicability across a wide range of synthetic and biological systems. We show that the site sensitivity of exchange coupling allows distinct triplet pairs to be resonantly addressed at different magnetic fields, tuning them between optically bright singlet ([Formula: see text]) and dark triplet quintet ([Formula: see text]) configurations: This induces narrow holes in a broad optical emission spectrum, uncovering exchange-specific luminescence. Using fields up to 60 T, we identify three distinct triplet-pair sites, with exchange couplings varying over an order of magnitude (0.3-5 meV), each with its own luminescence spectrum, coexisting in a single material. Our results reveal how site selectivity can be achieved for organic spin pairs in a broad range of systems.
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19
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Cabero Zabalaga M, Wei J, Yang H, Fan BB, Sun Y, Zhao W. Unraveling the Characteristic Shape for Magnetic Field Effects in Polymer-Fullerene Solar Cells. ACS OMEGA 2017; 2:7777-7783. [PMID: 31457335 PMCID: PMC6645333 DOI: 10.1021/acsomega.7b01470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 10/31/2017] [Indexed: 06/10/2023]
Abstract
Spin-dependent effects in organic solar cells (OSCs) are responsible for tuning the electric current when an external magnetic field is applied. Here, we report the magnetic field effect (MFE) on wide-bandgap (WBG) solar cells based on the polymers PBDT(O)-T1 and PBDT(Se)-T1 blended with PC70BM. Furthermore, we propose an experimental method based on the electrical transport (i-V) measurements to unveil the negative magneto conductance (MC) at small bias. The observed curves in a double-logarithmic scale display a particular S-like shape, independent of the OSC power conversion efficiency (PCE) or MC amplitudes. Additionally, from the slope of the S-like shape curve, it is possible to identify the fullerene concentrations that would result in the minimum MC and the maximum PCE. Our work opens up a door to find more patterns to describe MFE and PCE in polymer-fullerene solar cells, without the application of external magnetic or luminous sources.
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Affiliation(s)
- Marco
Antonio Cabero Zabalaga
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Jiaqi Wei
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Huaiwen Yang
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Bing Bing Fan
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Yanming Sun
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Weisheng Zhao
- Fert Beijing Institute, BDBC, School of Electronic and Information
Engineering, and Heeger Beijing
Research and Development Center, School of Chemistry and Environment, Beihang University, Beijing 100191, China
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20
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Sun X, Vélez S, Atxabal A, Bedoya-Pinto A, Parui S, Zhu X, Llopis R, Casanova F, Hueso LE. A molecular spin-photovoltaic device. Science 2017; 357:677-680. [DOI: 10.1126/science.aan5348] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/12/2017] [Indexed: 01/18/2023]
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21
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Li L, Zhang Z, Ren S, Zhang B, Yang S, Cao B. Construction of hollow Co3O4cubes as a high-performance anode for lithium ion batteries. NEW J CHEM 2017. [DOI: 10.1039/c7nj01432e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We report on hollow Co3O4cubes synthesizedviaa self-sacrificing template method and their application as an anode material for reversible electrochemical lithium storage.
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Affiliation(s)
- Li Li
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
| | - Zichao Zhang
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
| | - Sijia Ren
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
| | - Bingke Zhang
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
| | - Shuhua Yang
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
| | - Bingqiang Cao
- School of Material Science and Engineering
- Materials Research Center for Energy and Photoelectrochemical Conversion
- University of Jinan
- Jinan 250022
- China
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22
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Tajima H, Nishioka Y, Sato S, Suzuki T, Kimata M. Magnetic field effects of photocarrier generation in bulk heterojunctions at low temperature. Dalton Trans 2016; 45:16616-16623. [PMID: 27484333 DOI: 10.1039/c6dt02132h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report an experimental investigation of the magnetic field effect (MFE) in polymer bulk heterojunction devices at temperatures below 10 K using photocarrier extraction by linearly increasing voltages. The examined devices were composed of an active layer of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester. In the experiments, the delay time (td) dependence of the MFE was investigated in detail. For td < 80 μs, a positive MFE was observed in the field region B < 0.1 T and a negative MFE was observed for B > 0.2 T. For td > 8 ms, only a positive MFE proportional to B2 was observed. For the photocurrent pulse detected immediately after light irradiation, the MFE was negligibly small. In a high magnetic field of 15 T, a significant MFE exceeding 80% was observed at 1.8 K for td = 800 ms. We discuss the results based on a model of triplet-singlet (or singlet-triplet) conversion in the magnetic field and estimate the exchange integral for the charge-transfer exciton in this photovoltaic cell.
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Affiliation(s)
- H Tajima
- Graduate School of Material Science, University of Hyogo, 3-2-1 Kohto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
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23
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Jia W, Chen Q, Chen Y, Chen L, Xiong Z. Magneto-conductance characteristics of trapped triplet-polaron and triplet-trapped polaron interactions in anthracene-based organic light emitting diodes. Phys Chem Chem Phys 2016; 18:30733-30739. [PMID: 27792226 DOI: 10.1039/c6cp06322e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effects of a magnetic field on the dissociation of triplet excitons by free charges (TCI) are well understood. However, the magneto-conductance (MC) characteristics of trapped triplet-polaron interactions (TtPI) and triplet-trapped polaron interactions (TPtI) within organic light emitting diodes (OLEDs) are not well understood. We have studied these interactions in an anthracene-based OLED. The electroluminescence spectra, current-voltage characteristics and magneto-electroluminescence indicated that the anthracene layer contained many defects that could trap either triplet excitons or polarons, which led to TPtI and TtPI. The MC curves at low temperature exhibited a complex line shape, which indicated that intersystem crossing, TPtI, TtPI, and TCI occurred simultaneously in the device. The individual MC characteristics of TPtI and TtPI were extracted from temperature dependant MC curves by fitting them to three empirical Lorentzian functions and one non-Lorentzian function. The MC of TPtI exhibited a negative sign, while that of TtPI exhibited a positive one, with characteristic magnetic fields (B0) of ∼10.5 and ∼15 mT, respectively. Both processes were prominent below 150 K and weakened with increasing temperature. TPtI was neglected above 200 K, while TtPI was observed even at ambient temperature. These results add significant insight into the magnetic field effects on triplet-polaron interactions.
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Affiliation(s)
- Weiyao Jia
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, People's Republic of China.
| | - Qiusong Chen
- Department of Materials Science, Fudan University, Shanghai, 200433, People's Republic of China
| | - Yingbing Chen
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, People's Republic of China.
| | - Lixiang Chen
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, People's Republic of China.
| | - Zuhong Xiong
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, People's Republic of China.
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24
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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25
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Klein M, Pankiewicz R, Zalas M, Stampor W. Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture. Sci Rep 2016; 6:30077. [PMID: 27440452 PMCID: PMC4954973 DOI: 10.1038/srep30077] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/29/2016] [Indexed: 11/15/2022] Open
Abstract
The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.
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Affiliation(s)
- M. Klein
- Department of Physics of Electronic Phenomena, Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland
| | - R. Pankiewicz
- Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614 Poznan, Poland
| | - M. Zalas
- Faculty of Chemistry, Adam Mickiewicz University in Poznan, Umultowska 89b, 61-614 Poznan, Poland
| | - W. Stampor
- Department of Physics of Electronic Phenomena, Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
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26
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Mohanty D, Dahlberg K, King DM, David LA, Sefat AS, Wood DL, Daniel C, Dhar S, Mahajan V, Lee M, Albano F. Modification of Ni-Rich FCG NMC and NCA Cathodes by Atomic Layer Deposition: Preventing Surface Phase Transitions for High-Voltage Lithium-Ion Batteries. Sci Rep 2016; 6:26532. [PMID: 27226071 PMCID: PMC4880920 DOI: 10.1038/srep26532] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/03/2016] [Indexed: 02/08/2023] Open
Abstract
The energy density of current lithium-ion batteries (LIBs) based on layered LiMO2 cathodes (M = Ni, Mn, Co: NMC; M = Ni, Co, Al: NCA) needs to be improved significantly in order to compete with internal combustion engines and allow for widespread implementation of electric vehicles (EVs). In this report, we show that atomic layer deposition (ALD) of titania (TiO2) and alumina (Al2O3) on Ni-rich FCG NMC and NCA active material particles could substantially improve LIB performance and allow for increased upper cutoff voltage (UCV) during charging, which delivers significantly increased specific energy utilization. Our results show that Al2O3 coating improved the NMC cycling performance by 40% and the NCA cycling performance by 34% at 1 C/-1 C with respectively 4.35 V and 4.4 V UCV in 2 Ah pouch cells. High resolution TEM/SAED structural characterization revealed that Al2O3 coatings prevented surface-initiated layered-to-spinel phase transitions in coated materials which were prevalent in uncoated materials. EIS confirmed that Al2O3-coated materials had significantly lower increase in the charge transfer component of impedance during cycling. The ability to mitigate degradation mechanisms for Ni-rich NMC and NCA illustrated in this report provides insight into a method to enable the performance of high-voltage LIBs.
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Affiliation(s)
- Debasish Mohanty
- Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | | | - David M King
- PneumatiCoat Technologies, LLC, Broomfield, CO, USA
| | - Lamuel A David
- Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Athena S Sefat
- Materials Science and Technology Division, Oak Ridge National Laboratory, oak Ridge, TN, USA
| | - David L Wood
- Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, USA
| | - Claus Daniel
- Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.,Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, USA
| | - Subhash Dhar
- Energy Power Systems, LLC, Pontiac, MI, USA.,XALT Energy, LLC, Midland, MI, USA
| | | | | | - Fabio Albano
- Department of Materials Science and Engineering, University of Michigan Ann Arbor, 2300 Hayward St, Ann Arbor, MI, 48109, USA
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27
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Chen L, Yang Y, Gao Y, Tronganh N, Chen F, Lu M, Jiang Y, Jiao Z, Zhao B. Facile synthesis of ultrathin, undersized MoS2/graphene for lithium-ion battery anodes. RSC Adv 2016. [DOI: 10.1039/c6ra19601b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Ultrathin (∼5 layers), undersized (130–160 nm in size) MoS2/graphene composites are fabricated by a facile acetic acid assisted hydrothermal route.
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Affiliation(s)
- Lu Chen
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yaqing Yang
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yang Gao
- Shanghai Applied Radiation Institute
- Shanghai University
- Shanghai 201800
- P. R. China
| | - Nguyen Tronganh
- Shanghai Applied Radiation Institute
- Shanghai University
- Shanghai 201800
- P. R. China
- Faculty of Chemical and Environmental Engineering
| | - Fang Chen
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Mengna Lu
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yong Jiang
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Zheng Jiao
- Shanghai Applied Radiation Institute
- Shanghai University
- Shanghai 201800
- P. R. China
| | - Bing Zhao
- Shanghai Applied Radiation Institute
- Shanghai University
- Shanghai 201800
- P. R. China
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28
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Li M, He L, Xu H, Shao M, Tisdale J, Hu B. Interaction Between Optically-Generated Charge-Transfer States and Magnetized Charge-Transfer States toward Magneto-Electric Coupling. J Phys Chem Lett 2015; 6:4319-4325. [PMID: 26722968 DOI: 10.1021/acs.jpclett.5b01838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This article reports the magneto-dielectric studies on the coupling between optically generated CT states and magnetized CT states based on thin-film devices with the architecture of ITO/TPD:BBOT/TPD/Co/Al. The magnetized CT states are generated at the Co/TPD interface, generating a magneto-dielectric response with a broad, non-Lorentzian line-shape. The optically generated CT states are formed at the TPD:BBOT interfaces in the heterojunction under photoexcitation, leading to a magneto-dielectric signal with a narrow, Lorentzian line-shape. We find that combining the optically generated CT states and magnetized CT states yields a new magneto-dielectric signal with distinctive line-shape and amplitude in the ITO/TPD:BBOT/TPD/Co/Al device. The magneto-dielectric analysis indicates that there exists a coupling between optically generated CT states and magnetized CT states through the interactions between the magnetic Co/TPD interface and the optically excited TPD:BBOT heterojunction. Furthermore, we show that the coupling between optically generated CT states and magnetized CT states experiences Coulomb interactions and spin-orbital interaction by changing (i) the density of optically generated CT states and (ii) the separation distance between optically generated CT states and magnetized CT states. Clearly, this coupling provides a new approach to mutually tune magnetic and electronic properties through thin-film engineering by combining magnetic and organic materials.
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Affiliation(s)
- Mingxing Li
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
| | - Lei He
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
| | - Hengxing Xu
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
| | - Ming Shao
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
| | - Jeremy Tisdale
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
| | - Bin Hu
- Department of Materials Science and Engineering, University of Tennessee-Knoxville , Knoxville, Tennessee 37996, United States
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Spin-dependent recombination probed through the dielectric polarizability. Nat Commun 2015; 6:8534. [PMID: 26439933 PMCID: PMC4600752 DOI: 10.1038/ncomms9534] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/28/2015] [Indexed: 12/25/2022] Open
Abstract
Despite residing in an energetically and structurally disordered landscape, the spin degree of freedom remains a robust quantity in organic semiconductor materials due to the weak coupling of spin and orbital states. This enforces spin-selectivity in recombination processes which plays a crucial role in optoelectronic devices, for example, in the spin-dependent recombination of weakly bound electron-hole pairs, or charge-transfer states, which form in a photovoltaic blend. Here, we implement a detection scheme to probe the spin-selective recombination of these states through changes in their dielectric polarizability under magnetic resonance. Using this technique, we access a regime in which the usual mixing of spin-singlet and spin-triplet states due to hyperfine fields is suppressed by microwave driving. We present a quantitative model for this behaviour which allows us to estimate the spin-dependent recombination rate, and draw parallels with the Majorana-Brossel resonances observed in atomic physics experiments.
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Jiang H, Ren D, Wang H, Hu Y, Guo S, Yuan H, Hu P, Zhang L, Li C. 2D Monolayer MoS₂-Carbon Interoverlapped Superstructure: Engineering Ideal Atomic Interface for Lithium Ion Storage. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:3687-95. [PMID: 25989160 DOI: 10.1002/adma.201501059] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/23/2015] [Indexed: 05/26/2023]
Abstract
A novel strategy for the controlled synthesis of 2D MoS2/C hybrid nanosheets consisting of the alternative layer-by-layer interoverlapped single-layer MoS2 and mesoporous carbon (m-C) is demonstrated. Such special hybrid nanosheets with a maximized MoS2 /m-C interface contact show very good performance for lithium-ion batteries in terms of high reversible capacity, excellent rate capability, and outstanding cycling stability.
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Affiliation(s)
- Hao Jiang
- Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Dayong Ren
- Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Haifeng Wang
- State Key Laboratory of Chemical Engineering, Centre for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai, 200237, China
| | - Yanjie Hu
- Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Shaojun Guo
- Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Haiyang Yuan
- State Key Laboratory of Chemical Engineering, Centre for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai, 200237, China
| | - Peijun Hu
- State Key Laboratory of Chemical Engineering, Centre for Computational Chemistry and Research Institute of Industrial Catalysis, East China University of Science and Technology, Shanghai, 200237, China
- School of Chemistry and Chemical Engineering, The Queen's University of Belfast, Belfast, BT9 5AG, UK
| | - Ling Zhang
- Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai, 200237, China
| | - Chunzhong Li
- Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology, Shanghai, 200237, China
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