首页|Photophysical Properties and Photovoltaic Performance of Sensitizers with a Bipyrimidine Acceptor
Photophysical Properties and Photovoltaic Performance of Sensitizers with a Bipyrimidine Acceptor
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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,MOS2P-Pyc,and MOTS2P-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 兀-bridge improved the DSSC efficiency to 4.47%for MOTS2P-Pyc.Conversely,replacing the phenyl group with a thienothiophene block reduced DSSC efficiency to 2.14%for MOS2P-Pyc.Given the proton-accepting ability of the bipyrimidine module,we treated the dye-sensitized TiO2 photoanodes with hydroiodic acid(HI),significantly broadening the light absorption range.This treat-ment greatly enhanced the short-circuit current density of DSSCs owing to the enhanced electron-withdrawing ability of the acceptor.Consequently,the HI-treated MOTS2P-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.
Bipyrimidine acceptorMolecular engineeringPhotophysical processesCharge separationDye-sensitized solar cellsAcidichromic property
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