Molecular Design and Interface Engineering of Self-Assembled Monolayers for Inverted Perovskite Solar Cells: A Data-Driven Review of Efficiency, Stability and Scalability

Self-assembled monolayers (SAMs) have become indispensable hole-transport layers in inverted perovskite solar cells which enables power conversion efficiencies (PCEs) above 27% in single-junction devices and above 32% in tandems where the tandem devices benefit disproportionately from SAM engineering with certified efficiencies exceeding 31%. In the review eight hypotheses have been proposed including the prediction that bisphosphonic acid SAMs will outperform monophosphonic acid SAMs in thermal stability, glycol ether side chains will improve both PCE and stability and machine learning can identify new SAMs with >27% PCE and >90% retention at 1000 h , the studied researches shows that carbazole-based SAMs with phosphonic acid anchoring groups dominate the field with Me-4PACz and MeO-2PACz . Co-SAM strategies that have hydrogen-bonding additives consistently improve PCE by (1–3)% absolute over single-component SAMs and that bisphosphonic acid anchoring groups are emerging as a way to improve thermal and damp heat stability. Operational stability under maximum power point tracking now exceeds 1000 h for optimized SAM systems though ISOS protocol adoption remains inconsistent.