Impact of π-spacer on dye-sensitized solar cells and non-linear optical performance: Styryl vs imine vs azo

Abstract

Julolidine-based dyes, having a benzoic acid anchoring group, conjugated through different π-bridges (styryl, imine, and azo) have been investigated. It is discovered that the charge transfer (CT) characteristics of the dye system are changed as the π-bridges become less symmetrical. According to TD-DFT studies, the vertical absorption maximum shifts to the red region when the “N” atom is added to the styryl backbone. Computed photovoltaic characteristics, however, indicate that these dyes perform poorly when the “N” atom is added to the styryl backbone. Studies on dye@TiO2 clusters showa possible bonding between these dyes and TiO2, which would cause dye@TiO2 cluster absorption to shift red. Conversely, computed results of linear and non-linear optical (NLO) properties exhibit opposite patterns to those observed in dye-sensitized solar cell (DSSC) performance.Julolidine-based dyes with imine and azo linkers combined with benzoic acid were created and evaluated as DSSC sensitizers to determine their practical application. In agreement with DFT findings, experimental absorption in dimethylformamide (DMF) and cyclic voltammetry (CV) study verified the essential need for HOMO and LUMO energy levels. High thermal stability is indicated by the thermogravimetric analysis (TGA) results, which supports practical applications in DSSCs and non-linear optics (NLO). The efficiency patterns of the fabricated DSSC cells were similar, with JNNC showing the lowest efficiency (0.07 ± 0.02) and JCNC-OH demonstrating the highest (1.94 ± 0.02).