Efficient and Stable Graded CsPbI_3−xBr_x Perovskite Solar Cells and Submodules by Orthogonal Processable Spray Coating

Inorganic perovskite solar cells (PSCs) are promising for achieving long-term operational stability with good device performance. Here, we report the fabrication of inorganic CsPbI₂Br-based perovskite thin films with a well-defined CsPbI_3−xBr_x composition gradient in the surface region by a scalable, orthogonal processable spray-coating approach. The graded structure broadens absorption wavelength range and increases carrier lifetime, but it also causes electrical field redistribution within a device stack for more efficient charge separation and collection. With this approach, we obtained a power conversion efficiency of 16.81% for a 0.096-cm² PSC. We further demonstrated a monolithically integrated perovskite submodule based on the graded CsPbI_3−xBr_x by spray coating with an efficiency of 13.82% (112-cm² aperture area) and ∼9% degradation over 1,000-h continuous 1-sun light soaking. Solution-processed CsPbI₂Br thin films often suffer from poor film properties, which are indictive of electronic defects that can lead to poor stability. In addition, significant efforts are required to reduce the large cell-to-module performance gap for inorganic perovskite PV devices. Here, we report the fabrication of inorganic CsPbI₂Br-based perovskite thin films with a well-defined CsPbI_3−xBr_x composition gradient by a scalable, orthogonal processable spray-coating approach. The graded structure broadens the absorption wavelength range, increases carrier lifetime, and facilitates charge separation and collection. With this approach, we demonstrated a monolithically integrated perovskite submodule based on the graded CsPbI_3−xBr_x by spray coating with an efficiency of 13.82% (112-cm² aperture area) and ∼9% degradation over 1,000-h continuous 1-sun light soaking. The fabrication of inorganic CsPbI₂Br-based perovskite thin films with a well-defined CsPbI_3−xBr_x composition gradient in the surface region by a scalable, orthogonal processable spray-coating approach is reported. The graded structure broadens absorption wavelength range, increases carrier lifetime, and causes electrical field redistribution for more efficient charge separation and collection. With this approach, we obtained a power conversion efficiency of 16.81% for a 0.096-cm² cell and13.82% for a 112-cm² submodule with ∼9% degradation over 1,000-h 1-sun light soaking.