Interface configuration effects on excitation,exciton dissociation,and charge recombination in organic photovoltaic heterojunction |
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Authors: | Rui-Rong Bai Cai-Rong Zhang You-Zhi Wu Li-Hua Yuan Mei-Ling Zhang Yu-Hong Chen Zi-Jiang Liu Hong-Shan Chen |
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Affiliation: | 1. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, China Department of Applied Physics, Lanzhou University of Technology, Lanzhou, China;2. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, China;3. Department of Applied Physics, Lanzhou University of Technology, Lanzhou, China;4. Department of Physics, Lanzhou City University, Lanzhou, China;5. College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, China |
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Abstract: | The morphology of donor-acceptor heterojunction interface significantly affects the electron/hole processes in organic solar cells, including charge transfer (CT), exciton dissociation (ED), and charge recombination (CR). Here, to investigate interface molecular configuration effects, the donor-acceptor complexes with face-on, edge-on, and end-on configurations were constructed as model systems for the p-SIDT(FBTTh2)2/C60 heterojunction. The geometries, electronic structures, and excitation properties of monomers and the complexes with three configurations were studied based on density functional theory (DFT) and time-dependent DFT calculations with optimally tuned range separation parameters and solid polarization effects. In terms of Marcus theory, the rate constants of ED and CR processes were analyzed. The results show that most of the excited states for p-SIDT(FBTTh2)2 exhibit an intramolecular CT character, and the similarity of the excitation characters (CT and local excitation) and energies among three complexes with different configurations indicate that the electronic structure and excitation properties are insensitive to the interfacial molecular configurations. However, the rates of ED and CR processes heavily depend on it. These results underline the importance of controlling molecular configuration and then the morphology at the heterojunction interface in organic solar cells. |
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Keywords: | charge recombination charge transfer electronic structure organic heterojunction interface |
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