Amorphous Silica Interlayer Unlocks Direct Epitaxial Growth of CsPbBr₃ on Silicon via Slip-and-Stick Mechanism

In this study, we investigate the “Slip and Stick” mechanism governing the epitaxial growth of CsPbBr₃ on amorphous silica surfaces and its implications for silicon/perovskite tandem solar cell applications. The unique, low-energy diffusion behavior of cesium lead bromide on amorphous silica enables molecular species to traverse the surface efficiently without bond-breaking, thereby preserving structural integrity. Consequently, the chemically inert nature of amorphous silica facilitates the formation of crystalline CsPbBr₃ thin films on silicon substrates, which is essential for tandem solar cell architectures. In contrast, the reactive silicon (111) surface, that induces fragment decomposition and Br doping of Si, poses challenges to device stability due to potential disruptions in structural and electronic continuity. Our findings elucidate the observed difficulties in epitaxially growing metal halide perovskites directly on silicon surfaces and underscore the role of amorphous silica as an ideal passivation layer, promoting the precise layer-by-layer assembly necessary for high-efficiency tandem solar cells.