A Theoretical Study on the Underlying Factors of the Difference in Performance of Organic Solar Cells Based on ITIC and Its Isomers
Si-Qi Huang,
Li-Li Wang,
Qing-Qing Pan,
Zhi-Wen Zhao,
Ying Gao,
Zhong-Min Su
Affiliations
Si-Qi Huang
College of Chemical Engineering, Hubei University of Arts and Science, Xiangyang 441053, China
Li-Li Wang
Jilin Provincial Key Laboratory of Straw–Based Functional Materials, Institute for Interdisciplinary Biomass Functional Materials Studies, Jilin Engineering Normal University, Changchun 130052, China
Qing-Qing Pan
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Jilin Provincial International Joint Research Center of Photo-Functional Materials and Chemistry, Changchun 130022, China
Zhi-Wen Zhao
College of Chemical Engineering, Hubei University of Arts and Science, Xiangyang 441053, China
Ying Gao
Jilin Provincial Key Laboratory of Straw–Based Functional Materials, Institute for Interdisciplinary Biomass Functional Materials Studies, Jilin Engineering Normal University, Changchun 130052, China
Zhong-Min Su
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Jilin Provincial Science and Technology Innovation Center of Optical Materials and Chemistry, Jilin Provincial International Joint Research Center of Photo-Functional Materials and Chemistry, Changchun 130022, China
Recently, non-fullerene-based organic solar cells (OSCs) have made great breakthroughs, and small structural differences can have dramatic impacts on the power conversion efficiency (PCE). We take ITIC and its isomers as examples to study their effects on the performance of OSCs. ITIC and NFBDT only differed in the side chain position, and they were used as models with the same donor molecule, PBDB-T, to investigate the main reasons for the difference in their performance in terms of theoretical methods. In this work, a detailed comparative analysis of the electronic structure, absorption spectra, open circuit voltage and interfacial parameters of the ITIC and NFBDT systems was performed mainly by combining the density functional theory/time-dependent density functional theory and molecular dynamics simulations. The results showed that the lowest excited state of the ITIC molecule possessed a larger ∆q and more hybrid FE/CT states, and PBDB-T/ITIC had more charge separation paths as well as a larger kCS and smaller kCR. The reason for the performance difference between PBDB-T/ITIC and PBDB-T/NFBDT was elucidated, suggesting that ITIC is a superior acceptor based on a slight modulation of the side chain and providing a guiding direction for the design of superior-performing small molecule acceptor materials.
