Synthesis and characterization of new purple and green heterocyclic dyes for dye-sensitized solar cells

Abstract

Due to the growing demand for energy from industrial activities, solar energy has gained increasing attention globally. In recent years, heterocyclic dyes have gained attention due to their potential use as organic photosensitizers in dye-sensitized solar cells (DSSCs). To develop new and effective synthetic dyes for DSSCs, a study was conducted to create new purple dyes 8-(4-chlorophenyl)-5-(hydroxyimino)-3H-imidazo[4′,5′:3,4]benzo[1,2-c]isoxazol-4(5H)-ylidene)-2-arylacetonitriles. These dyes were synthesized by reacting nitro derivatives of imidazo benzoxazole with arylacetonitriles in an alkaline media. Additionally, new fluorescent heterocyclic systems 3-(4-chlorophenyl)-6H-imidazo[4,5-a]isoxazolo[4,3-c]acridine-7-carbonitriles were obtained by heterocyclization of the purple dyes with SOCl2. The highest yield achieved in the synthesis of the title dyes is 74 %. The structures of the new purple and green heterocyclic dyes were confirmed through elemental analysis and spectroscopic data. The photophysical properties of the dyes were investigated using a UV–visible spectrophotometer and a fluorophotometer. The electrochemical characteristics of the purple dyes and fluorescent heterocyclic systems were also studied using cyclic voltammetry. The geometries of the dyes, as well as their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, were determined through theoretical calculations using density functional theory (DFT). Furthermore, the photovoltaic performance parameters of the new dyes were examined by analyzing their incident photon-to-current efficiency (IPCE) spectra and current-voltage (I-V) curves. The experimental results showed that the purple dyes exhibited remarkable photovoltaic performances, up to 6.55 %.