Photophysical Properties and Photovoltaic Performance of Sensitizers with a Bipyrimidine Acceptor  

作　　者：Shiling Liu Kun Gong Wei Li Dongzhi Liu Xueqin Zhou 

机构地区：[1]School of Chemical Engineering and Technology,Collaborative Innovation Center of Chemical Science and Engineering,Tianjin Engineering Research Center of Functional Fine Chemicals,Tianjin University,Tianjin 300072,China

出　　处：《Transactions of Tianjin University》2024年第5期406-418,共13页天津大学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.21776207 and 21576195)。

摘　　要：Molecular engineering is a crucial strategy for improving the photovoltaic performance of dye-sensitized solar cells(DSSCs). Despite the common use of the donor-π bridge-acceptor architecture in designing sensitizers, the underlying structure-performance relationship remains not fully understood. In this study, we synthesized and characterized three sensitizers: MOTP-Pyc, MOS_(2)P-Pyc, and MOTS_(2)P-Pyc, all featuring a bipyrimidine acceptor. Absorption spectra, cyclic voltammetry, and transient photoluminescence spectra reveal a photo-induced electron transfer(PET) process in the excited sensitizers. Electron spin resonance spectroscopy confirmed the presence of charge-separated states. The varying donor and π-bridge structures among the three sensitizers led to differences in their conjugation effect, influencing light absorption abilities and PET processes and ultimately impacting the photovoltaic performance. Among the synthesized sensitizers, MOTP-Pyc demonstrated a DSSC efficiency of 3.04%. Introducing an additional thienothiophene block into the π-bridge improved the DSSC efficiency to 4.47% for MOTS_(2)P-Pyc. Conversely, replacing the phenyl group with a thienothiophene block reduced DSSC efficiency to 2.14% for MOS_(2)P-Pyc. Given the proton-accepting ability of the bipyrimidine module, we treated the dye-sensitized TiO_(2) photoanodes with hydroiodic acid(HI), significantly broadening the light absorption range. This treatment greatly enhanced the short-circuit current density of DSSCs owing to the enhanced electron-withdrawing ability of the acceptor. Consequently, the HI-treated MOTS_(2)P-Pyc-based DSSCs achieved the highest power conversion efficiency of 7.12%, comparable to that of the N719 dye at 7.09%. This work reveals the positive role of bipyrimidine in the design of organic sensitizers for DSSC applications.

关 键 词：Bipyrimidine acceptor Molecular engineering Photophysical processes Charge separation Dye-sensitized solar cells Acidichromic property 

分 类 号：TM914.4[电气工程—电力电子与电力传动]