Multifunctional molecule interface modification for high-performance inverted wide-bandgap perovskite cells and modules

Wide-band gap (≥1.66 eV) inverted perovskite solar cells (PSCs) are important portions of tandem silicon/PSCs. However, the poor efficiency and phase stability are still unresolved and blocking the industrialization of the scalable inverted PSCs. An interface modification strategy was developed using a multifunctional molecule, pyridinyl-benzimidazolium chloride to stabilize the perovskite surface. The pyridine and benzimidazole groups can fulfill halide vacancies, saturate the uncoordinated Pb²⁺ sites, and bond with formamidinium/methylammonium cations. Benefitting from the interface defect passivation, reduced nonradiative recombination, and effective suppression of halide phase separation, a champion efficiency of 21.82% with a high V_oc of 1.24 V in the fabricated inverted-small-area PSCs was achieved at the 1.67 eV-bandgap perovskite. The unsealed PSCs presented high light stability and excellent storage stability of over 2000 h. The semitransparent mini-modules were also successfully fabricated with high efficiency of 18.05% at a 1.92 cm² active area. This multifunctional defect passivation strategy provides an important avenue for high-performance perovskite top cells for tandem photovoltaics.