Efficient and Stable Graded CsPbI3−xBrx 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 CsPbI3−xBrx 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 CsPbI3−xBrx 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. [Display omitted] •A graded CsPbI2Br/CsPbI3−xBrx composition structure by spray coating is reported•The graded structure broadens absorption and facilitates charge collection•Efficiencies of 16.81% for 0.096-cm2 and 13.82% for 112-cm2 devices are obtained•The 112-cm2 submodule shows ∼9% degradation after 1,000-h continuous 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 CsPbI3−xBrx 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 CsPbI3−xBrx 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 CsPbI3−xBrx 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