Achieving 32% Efficiency in Perovskite/Silicon Tandem Solar Cells with Bidentate-Anchored Superwetting Self-Assembled Molecular Layers

The inhomogeneity of hole-selective self-assembled molecular layers (SAMLs) often arises from the insufficient bonding between anchors and metal oxide, particularly on textured silicon surfaces when fabricating monolithic perovskite/silicon tandem solar cells (P/S-TSCs) and the hydrophobic carbazole complicates the fabrication of high-quality perovskite films. To address this, we developed a novel bidentate-anchored superwetting aromatic SAM based on an upside-down carbazole core as a hole-selective layer (HSL), denoted as ((9H-carbazole-3,6-diyl)bis(4,1-phenylene))bis(phosphonic acid) (2PhPA-CzH). The bisphosphonate-anchored exhibited enhanced adsorption capabilities and efficient hole extraction/transport, and the reversely substituted carbazole ring contributed a friendly super wetting underlayer that enabled high-quality perovskite films with minimized energetic mismatches, which 2PhPA-CzH played a pivotal role in dual interfacial energy regulation. Through these advancements, the optimized wide-bandgap (1.68 eV) PSCs demonstrated an improved PCE of 22.83% and excellent stability with T₉₀ exceeding 1000 h under damp-heat conditions (ISOS-D-3, 85% RH, 85 °C), representing one of the best performances for SAMs as HSL-based PSCs. Notably, 2PhPA-CzH-functionalized recombination layers extended to submicron-pyramid texture SHJ to fabricate P/S-TSCs, achieving an impressive efficiency of 32.19% at an active area of 1 cm² (certified 31.54%) while maintaining excellent photostability. This work offers guidance for designing multidentate-anchored SAMs to realize record PCE and excellent stability in P/S-TSCs.