Influence of m-fluorine substituted phenylene spacer dyes in dye-sensitized solar cells

Abstract

A series of new organic dyes based on fluorine substituted phenyl moiety, used as a π-linker in various dyes, were designed and synthesized for dye sensitized solar cell (DSSC) application. These dyes share same anchoring group (Cyano acrylic acid) with different donors such as carbazole, thiopene substituted carbazole, triphenylamine and phenothiazine moieties. For effective electron flow, the dyes were incorporated with novel D-π-A or D-A-A framework. The optical, electrochemical, time-resolved photoluminescence (TRPL) spectra and photovoltaic properties of the dyes were carefully studied. The results reveal that without addition of any co-adsorbent, among all fluoro-phenyl spacer dyes, the Cz-dye showed highest open circuit voltage (Voc), short circuit current (Jsc) and exhibited enhanced PCE value of 4.2 (±0.2) %, due to the deeper HOMO level of dye, planarity of backbone with better charge transfer occurring form D to A. The optimization calculations for the geometries of all the dyes with fluoro phenyl substituted π-linkers were ascertained by Density functional theory (DFT) using B3LYP/631G (d,p) basis set.