Mitigating Delamination in Perovskite/Silicon Tandem Solar Modules

Abstract

As perovskite/silicon tandem solar cells head toward industrialization, one emerging challenge relates to the mechanical reliability of these organic–inorganic multilayer devices. Herein, the fracture toughness and interfacial strength of monolithic p–i–n perovskite/silicon tandems are assessed in the context of module integration. While the weakest layer in the tandem stack investigated is found to be C₆₀, used here as electron-transport layer (interfacial tensile strength of 0.64 MPa), more concerningly, the fracture energy of the C₆₀/tin-oxide interface is found to be only 1.2 J m⁻². The low fracture toughness of perovskite/silicon tandems can encourage crack propagation and large-scale delamination during processes used for their integration into modules such as cell cutting, interconnection, and vacuum lamination. By improving the tin oxide buffer layer properties and reducing sputtering-induced internal stress (associated with the transparent top electrode deposition onto the tin the oxide buffer layer), the fracture energy is improved to over 160 J m⁻². A second strategy to mitigate delamination due to the low fracture toughness of the cells is tailoring encapsulation and cell processing techniques specifically toward the perovskite/silicon tandem technology. In this work, a critical reliability issue, relevant for any perovskite-based optoelectronic technology requiring device packaging, is addressed.