Minireview and Outlook of Carbazole and Phenothiazine-Modified Triphenylamines as Hole Transporting Materials for Enhancing Perovskite Solar Cells

Hybrid organic–inorganic halide perovskite solar cell technology has experienced remarkable efficiency growth, rising from 3.8% to over 27.0%. This swift progress can be attributed to the straightforward solution process, ease of large-scale manufacturing, and low production costs of perovskite-based thin-film solar cells, which have attracted considerable research interest. Additionally, the various layers present in perovskite solar cells, such as photo absorbers, electron transport layers, and hole transport layers, play a crucial role in enhancing both efficiency and stability. This Review focuses on the current designs, electrochemical properties, thermal performance, power conversion efficiency, stability, and density functional theory of newly developed hole transport materials, specifically carbazole- and phenothiazine-bearing triphenylamines, for use in perovskite solar cells.