Power conversion efficiency and its comparison of D-π-A and D-D-π-A structured photo-sensitizers

In this article as an extension of our prior research investigations, we discuss and compare the properties of indole-based D-π-A and D-D-π-A structured dyes and their photovoltaic performances. The photophysical aspects and electrochemical attributes of the previously reported D-π-A and D-D-π-A structured indole dyes were examined to figure out the thermodynamic feasibility of the dyes to perform as photosensitizers. Furthermore, these dyes were used to fabricate dye-sensitized solar cells (DSSCs) and their photovoltaic activity was assessed. The interfacial charge transfer in the DSSCs was identified using electrochemical impedance analysis (EIS). CB-K₂K₁S dye-based DSSC device expressed the fill factor (FF) of 0.65, contributing to the highest open-circuit voltage (V_OC) of 645.3 mV and highest efficiency (η) of 4.33% since it has the highest short-circuit current density (J_SC) of 9.8 mA cm^-2, in contrast to MB-K₂K₁ dye which displayed V_OC = 613.4 mV, J_SC = 7.6 mA cm^-2, FF = 0.63, η = 3.10%.