The inhomogeneity of hole-selective self-assembled molecular layers (SAMLs) often arises from the insufficient bonding between anchors and metal oxides, 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, researchers from the Chinese Academy of Sciences (CAS), Advanced Solar Technology Institute of Xuancheng and North Minzu University have developed a 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 super wetting underlayer that enabled high-quality perovskite films with minimized energetic mismatches, where 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.
