Triphenylamine-Appended Carbazole-Based Hole-Transport Layer for Perovskite Solar Cells Fabricated under Low Humidity

Perovskite solar cells (PSCs), renowned for their high power conversion efficiency (PCE), have organic–inorganic metal halide perovskites (OIMHPs), hole-transport materials (HTMs), and electron-transport materials (ETMs) as crucial components determining their performance and cost. Materials like spiro-OMeTAD and PTAA, which are widely employed as HTMs in high-efficiency PSCs, have difficult synthesis routes, low yields, and limited precursor availability. This results in high costs, which make them unsuitable for large-scale applications. This study explores the synthesis and fabrication of PSCs using a carbazole-based HTM, CBZ-BDMTPA, a 2,7-dimethoxytriphenylamine-appended carbazole, which has been successfully synthesized indigenously, ensuring both cost-effectiveness and better production yield compared to conventional HTMs. The synthesized HTM revealed absorption in the near-ultraviolet region, low oxidation potentials, and better thermal stabilities than similar HTM analogues. The PSCs fabricated under 10% humidity exhibited a PCE of 14.04%, similar to that of the reference devices fabricated with spiro-OMeTAD (14.5%). This ensures CBZ-BDMTPA as a promising alternative to the costlier high-performing HTM. Moreover, a peak external quantum efficiency of 80% ensured efficient charge collection by CBZ-BDMTPA.