Island-like silica coating for optical antireflection and interface passivation in perovskite solar cells with high short-circuit current density

Silica is widely utilized in perovskite solar cells owing to its tunable refractive index, exceptional optical transparency, and chemical stability, which collectively enhance light-harvesting efficiency, minimize reflection loss, and optimize light field distribution. However, the insulating nature of SiO 2 impedes charge transport, posing a challenge to the concurrent realization of antireflection and electrical modulation within the device. In this work, an island-like silica coating (ISC) was fabricated on the surface of SnO 2 , enabling synergistic antireflection and passivation effects. This architecture not only elevates the visible light transmittance of the electron transport layer but also effectively passivates interfacial defects, improves the uniformity of perovskite films, facilitates the growth of perovskite grains, and thereby significantly enhances device performance. Experimental results demonstrate that the ISC boosts the performance of formamidinium-based perovskite solar cells: the short-circuit current density increases from 24.61 mA·cm -2 to 25.85 mA·cm -2 , and the power conversion efficiency rises from 22.49 % to 24.43 %. Moreover, unencapsulated devices retain 90 % of their initial PCE after 30 days of storage in ambient air (humidity: 20 %–30 %, temperature: 25 °C) and maintain 86 % of their initial efficiency following 500 h of continuous maximum power point tracking testing in N 2 atmosphere. The ISC developed in this study offers a novel strategy for mitigating optical and electrical losses in perovskite solar cells.