CuInS2/Poly(triarylamine) (PTAA) binary composite as an efficient hole transporter for carbon electrode-based perovskite solar cells

•CuInS2/PTAA is used as HTL for mesoscopic-based perovskite solar cells.•Optimized energy level alignment, traps sites and defects passivation, and improved charge extraction obtained.•Efficiency improvement up to 16% after aging.•100% and 70% retained PCE after 1720 h in dark controlled medium and 408 h under thermal stress in ambient medium, respectively. Perovskite solar cells (PSCs) with doped 2,2′,7,7′-Tetrakis[N,N-di(4- methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD) hole transport layer HTL suffers from instability due to dopants' hygroscopic nature. To ensure stability, inorganic materials are used as replacements, but still suffer from several drawbacks that can compromise their HTL role. Herein, we introduce organic Poly(triarylamine) (PTAA) into CuInS2 inorganic HTL to form a binary composite that suppresses these drawbacks. Results show a better hole extraction and favorable energy level alignment in binary-based devices concerning CuInS2-only devices, resulting in improved power conversion efficiency (PCE) from 14.68 to 16% after aging. Stability tests indicate binary HTL-based devices' superior stability retaining their complete initial PCE after 1720 h in a dark inert medium (∼15% humidity), and 70% after 408 h in a thermally stressed ambient medium (60 °C-40% humidity). Experimentally, the results indicate superior performance of binary HTL-based devices due to better film morphology, passivated defects and trap, and superior charge extraction. [Display omitted]