Performance and Stability Enhancement of Hole-Transporting Materials in Inverted Perovskite Solar Cells

Perovskite solar cells (PSCs) with an inverted device configuration, commonly named as p-i-n architecture, hold significant promise for future commercialization owing to their scalable fabrication processes, reliable performance, and compatibility with a broad spectrum of tandem photovoltaics. Notably, the advancements in hole-transporting materials (HTMs) are pivotal in enhancing the power conversion efficiency (PCE) of inverted PSCs. This Spotlight article underscores the substantial progress in HTMs for p-i-n PSCs, particularly focusing on the design and application of self-assembled monolayer (SAM)-based molecules. The deposition of SAMs on transparent conductive oxides (TCOs) provides uniformly thin layers that minimize charge transport losses, thereby simultaneously improving open-circuit voltage and fill factors in PSCs. Further development of SAM molecular structures has enhanced their adsorption stability on TCOs, intrinsic molecular stability, and structural reliability at the perovskite-substrate interface. Finally, this Spotlight outlines prospective research directions and challenges of HTMs in PSCs.