Fine-tuning π-spacer for high efficiency performance DSSC: A theoretical exploration with D - π - A based organic dye

Based on density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, a series of triphenylamine based organic dyes that modified by electron-withdrawing (EW) or electron-deficient (ED) substituent groups are investigated. The properties of all the isolated dyes, including frontier molecular orbital, intramolecular charge transfer, absorption spectra, maximal photon generated current (J(ph)) and intermolecular interaction between dye and I-2 are investigated theoretically to confirm which dyes can produce great performance for dye-sensitized solar cell (DSSC). Subsequently, the structures of dye combined with (TiO2)(64) cluster are optimized by means of Vienna ab initio simulation package (VASP) code. Then the interfacial interaction between the dye and semiconductor is further discussed to reveal the interfacial charge injection process by means of interfacial electron transfer code. The importance of fine-tuning pi-spacer is also demonstrated by the density of state (DOS) plot and photo induced charge transfer dynamics. Compared with other dyes, TA-CN dye shows outstanding performance because of the strong coupling of the absorbed dye's orbitals with substrate orbitals and the fast as well as complete charge injection process. The purpose of our study is expected to provide a promising way to design possible candidate sensitizers for DSSC. (C) 2017 Elsevier Ltd. All rights reserved.