Recent developments in metal-free organic sensitizers derived from carbazole, triphenylamine, and phenothiazine for dye-sensitized solar cells

In the present context of increasing population, renewable and sustainable energy alternatives are very much essential to satisfy the necessities of the world. To satisfy this growing demand, scientists are prioritizing the production of cost-effective and high-performance clean energy appliances. Dye-sensitized solar cells (DSSCs) are one such material that is at the forefront of modern solar cell technologies. Being one of the main components of DSSCs, metal-free organic dyes play a crucial role in light processing and electron injection. In recent times, carbazole (CZ)-, triphenylamine (TPA)-, and phenothiazine (PTZ)-based derivatives have been identified as suitable alternatives to Ru(II) polypyridyl complexes because they are easy to synthesize and exhibit excellent thermal and electronic properties. This review focuses largely on the latest developments in the use of monoanchored and multianchored CZ, TPA, and PTZ scaffolds for DSSC applications and focuses especially on the correlation between molecular design and photovoltaic performance. The physical properties of devices can be adjusted through the sensitizer's strategic design that helps to improve the performance of the devices. We tabulated the photovoltaic parameters corresponding to all dyes presented in this review. Also, applications of additives are presented after the systematic review on CZ-, TPA-, and PTZ-based dyes.