Double-Side healing at CsPbI2Br/ZnO interface by bipyrimidine hydroiodide enables inverted solar cells with enhanced efficiency and stability.

[Display omitted] • A double-side healing strategy is applied to modify the CsPbI 2 Br/ZnO interface. • The conduction through perovskite grain is greatly improved via this strategy. • The built-in electric field across the perovskite film is remarkably enhanced. • A better electric contact at the CsPbI 2 Br/ZnO interface is achieved. • The inverted devices deliver a PCE of 15.36% and excellent operational stability. Inorganic perovskite solar cells (PSCs) with inverted (p-i-n) configuration are important for the development of tandem solar cells. Nevertheless, inverted all-inorganic PSCs still remain challenging due to the high-density defects in the perovskite and inorganic charge-transporting layer. Herein, we demonstrate a double-side healing strategy to simultaneously improve the performance of perovskite and electron transporting layer (ETL). Specifically, bipyrimidine hydroiodide (BP-HI) is introduced at the CsPbI 2 Br/ZnO interface in inverted PSC. A combined microscopic, mass spectrometric and spectroscopic study reveals that the BP-HI could diffuse into not only perovskite grain boundaries (GBs) but also the ZnO layer. This double-side healing leads to improved conduction through perovskite grain, suppressed ion-migration along perovskite GBs, enhanced built-in electric field cross perovskite film and better electric contact at the PVK/ZnO interface. As a result, the optimized PSCs deliver a champion PCE of 15.36% along with a stabilized power output (SPO) of 15.05%. Meanwhile, these PSCs also display excellent long-term operational stability under ambient conditions. This work thus provides a feasible route for improving the performance and stability of inverted PSCs. [ABSTRACT FROM AUTHOR]