Anchor Engineering of Hole-Selective Enamine-Based Self-Assembling Monolayers for Perovskite Solar Cells

The transition to renewable energy sources, particularly solar power, has highlighted the potential of next-generation perovskite solar cells (PSCs), which have achieved a power conversion efficiency (PCE) over 27%, rivaling conventional silicon solar cells. A critical component in p-i-n PSCs is hole transporting layer (HTL), where polymers like PTAA have shown promise but face challenges in efficiency and commercial viability hindered by high costs and complex synthesis. Recently, enamine-based HTMs have emerged as a promising alternative due to their superior charge transport properties, structure's tunability, and cost-effectiveness. Additionally, self-assembling monolayers (SAMs) have been explored to improve inverted PSC performance by enhancing interface properties and reducing material use. This study combines enamine chemistry and self-assembly to engineer enamine-based SAMs with various structural units having ─COOH and ─PO(OH)₂ anchoring groups to optimize SAM/TCO interface and reduce recombination losses. The resulting p-i-n devices exhibit high power conversion efficiencies (>25.5%) and improved stability. The champion mini-module with an aperture area of 29.7 cm² realizes a PCE of 23.14% with an FF of 83.11%, highlighting the potential of these materials for scalable photovoltaic applications.