The effect of relative position of the π-spacer center between donor and acceptor on the overall performance of D-π-A dye: a theoretical study with organic dye

Abstract

The influence of the relative position of π-spacer center between donor and acceptor on the dye-sensitized solar cell (DSSC) performance is expounded by analyzing the geometry, electronic structure, optical absorption property, and intramolecular charge transfer, as well as reorganization energy by means of density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches. The results based on electronic structure and absorption property indicate that the dyes with introduction of building blocks to p1 position will generate more efficient charge separated states and present red-shifted in spectra. According to the analysis of intramolecular charge transfer, the results show that although introducing building blocks to p1 position can not make all structures to reduce orbital overlap, all the dyes with relatively small distance between donor and π-spacer center can enhance the amount of qCT and DCT. Additionally, the dyes with building blocks are introduced to p1 position that give better charge transfer balance performance due to their smaller Λh and Λe values. That is to say, the dye with a rigidified-aromatic as π-spacer, properly adjusting the position of π-spacer center is a valid approach for achieving great performance of DSSC.