Reducing Perovskite/C₆₀ Interface Losses via Sequential Interface Engineering for Efficient Perovskite/Silicon Tandem Solar Cell

Wide-bandgap (WBG) perovskite solar cells hold tremendous potential for realizing efficient tandem solar cells. However, nonradiative recombination and carrier transport losses occurring at the perovskite/electron-selective contact (e.g. C₆₀ ) interface present significant obstacles in approaching their theoretical efficiency limit. To address this, a sequential interface engineering (SIE) strategy that involves the deposition of ethylenediamine diiodide (EDAI₂ ) followed by sequential deposition of 4-Fluoro-Phenethylammonium chloride (4F-PEACl) is implemented. The SIE technique synergistically narrows the conduction band offset and reduces recombination velocity at the perovskite/C₆₀ interface. The best-performing WBG perovskite solar cell (1.67 eV) delivers a power conversion efficiency (PCE) of 21.8% and an impressive open-circuit voltage of 1.262 V. Moreover, through integration with double-textured silicon featuring submicrometer pyramid structures, a stabilized PCE of 29.6% is attained for a 1 cm² monolithic perovskite/silicon tandem cell (certified PCE of 29.0%).