Temperature effect on polaron recombination in conjugated polymers |
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| Affiliation: | 1. Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany;2. Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 227, 69120, Heidelberg, Germany;3. Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 225, 69120, Heidelberg, Germany;1. Department of Chemistry, Tunghai University, Taichung 40704, Taiwan;2. Department of Electronic Engineering and Organic Electronics Research Center, Ming Chi University of Technology, New Taipei City 24301, Taiwan;3. Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan;1. Department of Electrical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India;2. Microelectronics Research Center, 10100 Burnet Road, Bldg. 160, University of Texas at Austin, Austin, TX 78758, United States;1. Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha, 410083, Hunan, China;2. School of New Energy Science and Engineering, Xinyu University, Xinyu, 338004, China;3. Department of Physics and Astronomy, University of Rochester, Rochester, 14627, NY, USA;4. Synergetic Innovation Center for Quantum Effects and Applications (SICQEA), Hunan Normal University, Changsha, 410081, China;1. Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, PR China;2. Center of Polymers and Organic Solids, Departments of Chemistry & Biochemistry, University of California, Santa Barbara, CA 93106, USA |
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| Abstract: | The microcosmic mechanism of electroluminescence in polymer light emitting diodes (PLEDs) is the recombination of the oppositely charged polarons. In previous studies, it has been demonstrated that the temperature-induced irregular lattice vibration may have non-negligible influence on polaron dynamics. Nevertheless, there are few reports about thermal effect on recombination process between polaron pair, although it is very important for the performance of PLEDs. In this paper, we adopt the modified one-dimensional tight-binding model, including to which the thermal random force, and explore the temperature effect on polaron collision driven by electric field with different strengths. The dynamical simulation is performed by using the non-adiabatic evolution method. The results show that under the influence of electric field, the oppositely charged polarons could recombine into either an exciton with one lattice distortion, or the mixed state of polaron pair and exciton with two lattice distortions. It depends on both field strength and temperature. Anyway, after including temperature effect, a significant improvement of exciton yield is obtained. In addition, the new-formed exciton could perform a random walk along the polymer chain driven by the thermal random force when its strength is large enough. If we further increase the temperature, the stability of exciton would become worse. |
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| Keywords: | Temperature effect Polaron Exciton Conjugated polymer |
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