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

Abstract

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 highefficiency 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 costeffectiveness 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.