Chemical Rounding Suppresses Morphology‐Induced Interfacial Losses in Perovskite–Silicon Tandem Solar Cells

Surface texturing in crystalline silicon solar cells imposes a fundamental trade‐off in perovskite‐silicon tandems: micrometer‐scale pyramids enable efficient light trapping but limit the conformal deposition of thin perovskite films with sub‐micrometer thickness, whereas reduced texture heights improve compatibility at the expense of optical performance and interfacial quality of the tandem device. Here, we address this challenge by combining precisely controlled submicron texturing with an ozone‐assisted chemical rounding treatment. The resulting silicon substrates feature smoothly rounded, symmetric submicron textures that suppress micro‐terrace formation and partial epitaxy at the amorphous silicon/crystalline silicon interface, while promoting more spatially uniform optoelectronic properties in the subsequently integrated top‐cell stack. The morphology‐engineered texture yields a monolithic perovskite–silicon tandem device with a power conversion efficiency of 33.25%, demonstrating that multiscale morphological control provides a powerful pathway to simultaneously improve the optical performance and interfacial quality of tandem solar cells.