Anti‐Solvent‐Free Preparation for Efficient and Photostable Pure‐Iodide Wide‐Bandgap Perovskite Solar Cells

Abstract The perovskite/silicon tandem solar cell (TSC) has attracted tremendous attention due to its potential to breakthrough the theoretical efficiency set for single‐junction solar cells. However, the perovskite solar cell (PSC) designed as its top component cell suffers from severe photo‐induced halide segregation owing to its mixed‐halide strategy for achieving desirable wide‐bandgap (1.68 eV). Developing pure‐iodide wide‐bandgap perovskites is a promising route to fabricate photostable perovskite/silicon TSCs. Here, we report efficient and photostable pure‐iodide wide‐bandgap PSCs made from an anti‐solvent‐free (ASF) technique. The ASF process is achieved by mixing two precursor solutions, both of which are capable of depositing corresponding perovskite films without involving anti‐solvent. The mixed solution finally forms Cs 0.3 DMA 0.2 MA 0.5 PbI 3 perovskite film with a bandgap of 1.68 eV. Furthermore, methylammonium chloride additive is applied to enhance the crystallinity and reduce the trap density of perovskite films. As a result, the pure‐iodide wide‐bandgap PSC delivers efficiency as high as 21.30 % with excellent photostability, the highest for this type of solar cells. The ASF method significantly improves the device reproducibility as compared with devices made from other anti‐solvent methods. Our findings provide a novel recipe to prepare efficient and photostable wide‐bandgap PSCs.