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Vong D, Maleki F, Novak EC, Daemen LL, Moulé AJ. Measuring Intermolecular Excited State Geometry for Favorable Singlet Fission in Tetracene. J Phys Chem Lett 2024; 15:1188-1194. [PMID: 38270396 DOI: 10.1021/acs.jpclett.3c02343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Singlet fission (SF) is the process of converting an excited singlet to a pair of excited triplets. Harvesting two charges from a single photon has the potential to increase photovoltaic device efficiencies. Acenes, such as tetracene and pentacene, are model molecules for studying SF. Despite SF being an endoergic process for tetracene and exoergic for pentacene, both acenes exhibit near unity SF quantum efficiencies, raising questions about how tetracene can overcome the energy barrier. Here, we use recently developed instrumentation to measure inelastic neutron scattering (INS) while optically exciting the model molecules using two different excitation energies. The spectroscopic results reveal intermolecular structural relaxation due to the presence of a triplet excited state. The structural dynamics of the combined excited state molecule and surrounding tetracene molecules are further studied using time-dependent density functional theory (TD-DFT), which shows that the singlet and triplet levels shift due to the excited state geometry, reducing the uphill energy barrier for SF to within kT.
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Affiliation(s)
- Daniel Vong
- Department of Materials Science and Engineering, University of California Davis, Davis, California 95616, United States
| | - Farahnaz Maleki
- Department of Chemical Engineering, University of California Davis, Davis, California 95616, United States
| | - Eric C Novak
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Luke L Daemen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Adam J Moulé
- Department of Chemical Engineering, University of California Davis, Davis, California 95616, United States
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Li W, Bao X, Wang C, Yao Y, Song J, Peng K, Xu S, Chen L, Guan Y, Niu L. Exploring charge generation and separation in tandem organic light-emitting diodes based on magneto-electroluminescence. NANOTECHNOLOGY 2024; 35:175203. [PMID: 38150721 DOI: 10.1088/1361-6528/ad18e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/27/2023] [Indexed: 12/29/2023]
Abstract
5,6,11,12-tetraphenylnaphthacene (rubrene) exhibits resonant energy properties (ES1,rub≈ 2ET1,rub), resulting in rubrene-based organic light-emitting diode (OLED) devices that undergo the singlet fission (STT) process at room temperature. This unique process gives rise to a distinct magneto-electroluminescence (MEL) profile, differing significantly from the typical intersystem crossing (ISC) process. Therefore, in this paper, we investigate charge generation and separation in the interconnector, and the mechanism of charge transport in tandem OLEDs at room temperature using MEL tools. We fabricate tandem OLEDs comprising green (Alq3) and yellow (Alq3:rubrene) electroluminescence (EL) units using different interconnectors. The results demonstrate that all devices exhibited significant rubrene emission. However, the MEL did not exhibit an STT process with an increasing magnetic field, but rather a triplet-triplet annihilation (TTA) process. This occurrence is attributed to direct carrier trapping within doped EL units, which hinders the transport of rubrene trapped charges, consequently prolonging the lifetime of triplet excitons (T1,rub). Thus, the increased T1,rubconcentration causes TTA to occur at room temperature, causing the rapid decrease of MEL in all devices under high magnetic fields. In devices where only the TTA process occurs, the TTA increases with the increasing current. Consequently, the high magnetic field of devices A-C is only related to TTA. Notably, there exists a high magnetic field TTA of device D in the Alq3/1,4,5,8,9,11-Hexaazatriphenylene-hexacarbonitrile interconnector regardless of the current. This occurs because both EL units in the device emit simultaneously, resulting in the triplet-charge annihilation process of Alq3in the high magnetic field of the MEL. Moreover, the rapid increase in MEL at low magnetic field across all devices is attributed to the ISC between Alq3polaron pairs. This entire process involves Förster and Dexter energy transfer. This article not only provides novel insights into charge generation and separation in the interconnector but also enhances our understanding of the microscopic mechanisms in tandem OLED devices.
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Affiliation(s)
- Wanjiao Li
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Xi Bao
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Cheng Wang
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Yu Yao
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Jiayi Song
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Keao Peng
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Shuang Xu
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Lijia Chen
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Yunxia Guan
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Lianbin Niu
- Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
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Wei F, Chen J, Zhao X, Wu Y, Wang H, Chen X, Xiong Z. High-Performance Hot-Exciton OLEDs via Fully Harvesting Triplet Excited States from Both the Exciplex Co-Host and the TBRb Emitter. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303192. [PMID: 37587760 PMCID: PMC10582462 DOI: 10.1002/advs.202303192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/12/2023] [Indexed: 08/18/2023]
Abstract
The high-level reverse intersystem crossing (HL-RISC, T2 → S1 ) process from triplet to singlet exciton, namely the "hot exciton" channel, has recently been demonstrated in the traditional fluorescent emitter of TBRb. Although it is a potential pathway to improve the utilization of non-radiative triplet exciton energy, highly efficient fluorescent organic light emitting diodes (FOLEDs) based on this "hot exciton" channel have not been developed. Herein, high-efficiency and low-efficiency roll-off FOLEDs are achieved through doping TBRb molecules into an energy-level matched exciplex co-host. Combining the low-level RISC (LL-RISC, EX3 → EX1 ) process in the exciplex co-host with the HL-RISC process of hot excitons in TBRb to fully harvest the triplet energy, a record-high external quantum efficiency (EQE) of 20.4% is obtained via a proper Dexter energy transfer of triplet excitons, realizing the efficiency breakthrough from fully fluorescent material-based OLEDs with TBRb as an end emitter. Furthermore, the fingerprint Magneto-electroluminescence (MEL) as a sensitive measuring tool is employed to visualize the "hot exciton" channel in TBRb, which also directly verifies the effective energy confinement and the full utilization of hot excitons. Obviously, this work paves a promising way for further fabricating high-efficiency TBRb-based FOLEDs for lighting and flat-panel display applications.
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Affiliation(s)
- Fuxian Wei
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Jing Chen
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Xi Zhao
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Yuting Wu
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Huiyao Wang
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Xiaoli Chen
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
| | - Zuhong Xiong
- Chongqing Key Laboratory of Micro & Nano Structure Optoelectronics, School of Physical Science and TechnologySouthwest UniversityChongqing400715P. R. China
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Song J, Guan Y, Wang C, Bao X, Li W, Chen L, Niu L. Investigations on exciton recombination and annihilation in TmPyPB-ETL OLEDs using magnetic field effects. Phys Chem Chem Phys 2023; 25:23783-23791. [PMID: 37622246 DOI: 10.1039/d3cp02332j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Although the effect of the electron transport layer (ETL) material TmPyPb on the electroluminescence performance of organic light-emitting diodes (OLEDs) has been extensively studied, the process of TmPyPb regulating exciton recombination and annihilation within the device is still unclear. Here, we fabricated devices of various TmPyPb thicknesses with and without ETL. Subsequently, we measured the magneto-electroluminescence (MEL) of these devices. Specifically, at the same luminance, the triplet-charge annihilation (TQA) process is more likely to occur as the thickness of TmPyPb increases, resulting in a decrease in the maximum luminance of devices. Due to electron leakage and exciton recombination region moving towards the cathode, leading to a decrease in luminance efficiency at first and then an enhancement with an increase in the thickness of TmPyPb. Furthermore, at room temperature, the application of a large bias voltage suppresses singlet fission (SF) processes by modulating the dissociation of singlet polaron pairs (PPS) and the concentration of triplet exciton (T1). This leads to the conversion of SF to the TQA process. At low temperatures, the bias voltage and temperature can regulate the concentration and lifetime of PPS and T1. Therefore, as the temperature decreases, the transition of SF → TQA → triplet-triplet annihilation (TTA) and TQA coexistence → TTA process occurs. Moreover, MEL responses of the TmPyPb-ETL device show a W-linear pattern owing to the combined effect of the hyperfine interaction (HFI) and Zeeman splitting at 145 K. Accordingly, we explored the electroluminescence (EL) performance of TmPyPB-ETL OLEDs and investigated the evolution of SF, TQA, and TTA processes using MEL. Our study revealed the effect of exciton recombination and annihilation in OLEDs with varying thicknesses of TmPyPb.
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Affiliation(s)
- Jiayi Song
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Yunxia Guan
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Cheng Wang
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Xi Bao
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Wanjiao Li
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Lijia Chen
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
| | - Lianbin Niu
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing, 401331, People's Republic of China.
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Song J, Wang C, Guan Y, Bao X, Li WJ, Chen L, Niu L. Mediation of exciton concentration on magnetic field effects in NPB : Alq 3-based heterojunction OLEDs. RSC Adv 2023; 13:23619-23625. [PMID: 37555095 PMCID: PMC10405046 DOI: 10.1039/d3ra03608a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 07/18/2023] [Indexed: 08/10/2023] Open
Abstract
Organic light-emitting diodes (OLEDs) are considered one of the most promising new display technologies owing to their advantages, such as all-solid-state, high color gamut, and wide viewing angle. However, in terms of special fields, the brightness, lifetime, and stability of the devices need further improvement. Therefore, heterojunction devices with different concentrations were prepared to regulate device brightness. The brightness of the bulk heterojunction device is enhanced by 9740 cd m-2, with a growth rate of about 26.8%. The impact of various temperatures and various exciton concentrations on the device magneto-conductance (MC) and magneto-electroluminescence (MEL) was investigated. Experimental results demonstrate that the exciton concentration inside the device can be tuned to improve optoelectronic properties and organic magnetic effects. The complex spin mixing process inside the bulk heterojunction device is deeply investigated, which provides a reliable basis for the design of bulk heterojunction devices.
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Affiliation(s)
- Jiayi Song
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Cheng Wang
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Yunxia Guan
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Xi Bao
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Wan Jiao Li
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Lijia Chen
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
| | - Lianbin Niu
- College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China
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Bai Y, Ni W, Sun K, Chen L, Ma L, Zhao Y, Gurzadyan GG, Gelin MF. Plenty of Room on the Top: Pathways and Spectroscopic Signatures of Singlet Fission from Upper Singlet States. J Phys Chem Lett 2022; 13:11086-11094. [PMID: 36417755 DOI: 10.1021/acs.jpclett.2c03053] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We investigate dynamic signatures of the singlet fission (SF) process triggered by the excitation of a molecular system to an upper singlet state SN (N > 1) and develop a computational methodology for the simulation of nonlinear spectroscopic signals revealing the SN → TT1 SF in real time. We demonstrate that SF can proceed directly from the upper state SN, bypassing the lowest excited state, S1. We determine the main SN → TT1 reaction pathways and show by computer simulation and spectroscopic measurements that the SN-initiated SF can be faster and more efficient than the traditionally studied S1 → TT1 SF. We claim that the SN → TT1 SF offers novel promising opportunities for engineering SF systems and enhancing SF yields.
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Affiliation(s)
- Yiting Bai
- School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Wenjun Ni
- School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Kewei Sun
- School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China
| | | | - Lin Ma
- School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangdong 510006, China
| | - Yang Zhao
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Gagik G Gurzadyan
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian 116024, China
| | - Maxim F Gelin
- School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China
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Wang T, Zhang BY, Zhang HL. Singlet Fission Materials for Photovoltaics: from Small Molecules to Macromolecules. Macromol Rapid Commun 2022; 43:e2200326. [PMID: 35703581 DOI: 10.1002/marc.202200326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/29/2022] [Indexed: 11/08/2022]
Abstract
Singlet fission (SF) is a spin-allowed process in which a singlet state splits into two triplet states. Materials that enable SF have attracted great attention in the last decade, mainly stemming from the potential of overcoming the Shockley-Queisser (SQ) limit in photoenergy conversion. In the past decade, a large number of new molecules exhibiting SF have been explored and many devices based on SF materials have been studied, though the mechanistic understanding is still obscure. This review focuses on the recent developments of SF materials, including small molecules, oligomers and polymers. The molecular design strategies and related mechanisms of SF are discussed. Then the dynamics of charge transfer and energy transfer between SF materials and other materials are introduced. Further, we discuss the progresses of implementing SF in photovoltaics. It is hoped that a comprehensive understanding to the SF materials, devices and mechanism may pave a new way for the design of next generation photovoltaics. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ting Wang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), Key Laboratory of Special Function Materials and Structure Design, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Bo-Yang Zhang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), Key Laboratory of Special Function Materials and Structure Design, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Hao-Li Zhang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), Key Laboratory of Special Function Materials and Structure Design, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.,Prof. H. L. Zhang, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, P. R. China
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Asako T, Suzuki S, Tanaka S, Ota E, Yamaguchi J. Synthesis of Decaarylanthracene with Nine Different Substituents. J Org Chem 2020; 85:15437-15448. [PMID: 33201696 DOI: 10.1021/acs.joc.0c02218] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A synthesis of decaarylanthracene with nine different substituents has been accomplished by a coupling/ring-transformation strategy. The oxidation of tetraarylthiophenes with four different substituents to the corresponding thiophene S-oxides and a [4 + 2] cycloaddition with a double benzyne precursor afforded a multiply arylated naphthalene derivative. Subsequently, the naphthalene derivative was converted into a naphthalyne, and then a [4 + 2] cycloaddition of another thiophene S-oxide provided decaarylanthracenes with nine different aryl groups.
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Affiliation(s)
- Takashi Asako
- Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan
| | - Shin Suzuki
- Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan
| | - Shuhei Tanaka
- Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan
| | - Eisuke Ota
- Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan
| | - Junichiro Yamaguchi
- Department of Applied Chemistry, Waseda University, 513 Wasedatsurumakicho, Shinjuku, Tokyo 162-0041, Japan
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Tang X, Pan R, Zhao X, Zhu H, Xiong Z. Achievement of High-Level Reverse Intersystem Crossing in Rubrene-Doped Organic Light-Emitting Diodes. J Phys Chem Lett 2020; 11:2804-2811. [PMID: 32191490 DOI: 10.1021/acs.jpclett.0c00451] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using the fingerprint magneto-electroluminescence trace, we observe a fascinating high-level reverse intersystem crossing (HL-RISC) in rubrene-doped organic light-emitting diodes (OLEDs). This HL-RISC is achieved from high-lying triplet states (T2,rub) transferred from host triplet states by the Dexter energy transfer to the lowest singlet states (S1,rub) in rubrene. Although HL-RISC decreases with bias current, it increases with lowering temperature. This is contrary to the temperature-dependent RISC from conventional thermally activated delayed fluorescence, because HL-RISC is an exothermic process instead. Moreover, owing to the competition of exciton energy transfer with direct charge trap, HL-RISC changes nonmonotonically with the dopant concentration and increases luminous efficiency to a maximum at 10% of rubrene, which is about ten times greater than that from the pure-rubrene device. Additionally, the HL-RISC process is not observed in bare rubrene-doped films because of the absence of T2,rub. Our findings pave the way for designing highly efficient orange fluorescent OLEDs.
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Affiliation(s)
- Xiantong Tang
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, China
| | - Ruiheng Pan
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044, China
| | - Xi Zhao
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, China
| | - Hongqiang Zhu
- Chongqing Key Laboratory of Photo-Electric Functional Materials, Chongqing Normal University, Chongqing 401331, China
| | - Zuhong Xiong
- School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, China
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Maley SM, Mawhinney RC. Computational insights into the electronic structure of TCNDQ and TCNP: the effect of Si substitution. Struct Chem 2019. [DOI: 10.1007/s11224-018-1265-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jia W, Ikoma T, Chen L, Zhu H, Tang X, Qu F, Xiong Z. Using magneto-electroluminescence as a fingerprint to identify the spin polarization and spin-orbit coupling of magnetic nanoparticle doped polymer light emitting diodes. RSC Adv 2019; 9:15845-15851. [PMID: 35521377 PMCID: PMC9064273 DOI: 10.1039/c9ra01501a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/26/2019] [Indexed: 01/08/2023] Open
Abstract
The spin polarization and spin-orbit coupling (SOC) in polymer light emitting diodes (PLEDs) with the active layer doped with Fe3O4 nanoparticles (NPs) were identified through magneto-electroluminescence (MEL). By comparing the MEL characteristics such as linewidth and magnitude between PLEDs with and without Fe3O4 dopant, we confirmed the existence of spin polarization, but ruled out the existence of SOC. Although the spin polarization is positive to electroluminescence, the brightness-current characteristics suggested that the current efficiency of the doped PLED does not improve. We attributed it to the current leakage caused by the Fe3O4 NPs in the active layer. This work is beneficial for us to further understand the effect of magnetic nanoparticle doping on the dynamic behavior of excitons and polaron pairs in organic semiconductor devices.
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Affiliation(s)
- Weiyao Jia
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
- MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University Chongqing 400715 People's Republic of China
- Graduate School of Science and Technology, Niigata University 2-8050 Ikarashi, Nishi-ku Niigata 950-2181 Japan
| | - Tadaaki Ikoma
- Graduate School of Science and Technology, Niigata University 2-8050 Ikarashi, Nishi-ku Niigata 950-2181 Japan
| | - Lixiang Chen
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
| | - Hongqiang Zhu
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
| | - Xiantong Tang
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
| | - Fenlan Qu
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
| | - Zuhong Xiong
- School of Physical Science and Technology, Southwest University Chongqing 400715 People's Republic of China
- MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University Chongqing 400715 People's Republic of China
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