Scalable Passivation of Perovskite Solar Cells Using Evaporated CsPbCl3

The suboptimal interfacial quality between the perovskite absorption layer and the electron‐transport layer constrains the performance of perovskite solar cells. Introducing an interface passivation layer is generally recognized as an effective method for addressing this issue. A uniform passivation film with a large area can be prepared using an evaporation technique. In this study, we designed and fabricated an inorganic CsPbCl3 passivation layer by the coevaporation of PbCl2 and CsCl. The evaporated passivator exhibited excellent interface passivation effects and a relatively low thickness sensitivity to device performance. As a result, the open‐circuit voltage of perovskite solar cells with a 1.68 eV perovskite absorber was improved by nearly 100 mV, and the device efficiency achieved was 21.84%, ranking as the highest efficiency based on the hybrid evaporation‐solution method. The proposed passivation approach has potential applications in large‐area perovskite solar cells.