Significant Enhancement in Photovoltaic Performances for C217-based Dye Sensitizers via Introducing Electron-withdrawing Substituents:a Theoretical Study

摘要

cqvip:Dye-sensitized solar cells(DSSCs) are one of the most promising photovoltaic technologies, and the development of efficient dye sensitizers, especially inexpensive metal-free organic dyes, is always crucial for fabricating new DSSC devices. In this paper, a series of novel metal-free dyes with the D-A-π-A structure were designed by introducing electron-withdrawing substituents into the C217 molecular skeleton, and then their photovoltaic parameters were predicted by means of density functional theory(DFT) and time-dependent DFT(TD-DFT) calculations in combination with the Marcus charge transfer model. Our results showed that compared with C217, the introduction of trifluoromethyl(-CF3), cyano(-CN), and nitryl(-NO2) can efficiently narrow the HOMO-LUMO gap, and remarkably enhance the dye’s sunlight harvesting. With the(TiO2)38 cluster model, the photoelectric conversion efficiency(PCE) for the C217 dye was predicted to be up to 9.82%, which is in good agreement with the measured value(9.6%~9.8%), suggesting that our scheme used in this paper is reliable. Based on the same method, the PCE of most designed dyes was estimated to exceed over 10%, denoting that the molecular design strategy recommended by us in this work is reasonable. Especially, the PCE values of the dye 1, 4, and 6 were found to be as high as 14.75%, 16.02% and 15.75% respectively, suggesting that these three dyes are potential candidates as efficient sensitizers, and are worth further experimental study.