Theoretical study on a high-efficient porphyrin-sensitizer in a local electric field: How does the local electric field affects the performance of dye-sensitized solar cells?

The local electric field formed between dye sensitizers and semiconductor interface is one of key factors to determine the overall performance of dye-sensitized solar cells (DSSCs). Herein, a strategy has been proposed to explore the influence of the local electric field on the functionality of DSSCs of YD2-O-C8 dye via calculating the relevant properties in various electric field strengths. The YD2-O-C8 dye has been systemically studied with density functional theory (DFT) and time-dependent DFT (TD-DFT) for its electronic structure and optical properties in tetrahydrofuran (THF) solution. The absorption spectra are gradually narrowing and blue-shifting while increasing the electric field strength. Two key parameters of the light harvesting efficiency (LHE) and the TiO2 conduction band shift (Delta E-cb) have been examined for the YD2-O-C8 sensitized TiO2 system. It is found that it is of great importance to reduce the charge accumulation on the TiO2 film, which lowers the electric field strength and shows the best performance of DSSCs. This study is expected to deepen our understanding of the function of local electric field and the operational principles of the DSSCs for further optimization. (C) 2015 Elsevier B.V. All rights reserved.