Additive Engineering Toward High‐Performance CsPbI3Perovskite Solar Cells

All‐inorganic perovskite solar cells (PSCs) have attracted a lot of attention in the past few years because of their preeminent thermal stability compared with organic–inorganic hybrid PSCs. Among all kinds of all‐inorganic perovskites, CsPbI 3 perovskite with a proper bandgap of ≈1.7 eV becomes the most competitive candidate. However, its poor phase stability, hydrophobicity, and high‐density defects have limited the development of CsPbI 3 PSCs. To overcome these obstacles for achieving high‐performance CsPbI 3 PSCs, additive engineering has been widely used, which has rapidly promoted the power conversion efficiency (PCE) to over 19%. Herein, the progress of additive engineering in CsPbI 3 PSCs is systematically reviewed. First, the roles of additives in CsPbI 3 PSCs are introduced, including improving phase stability, increasing moisture resistance, and passivating defects. Then, the additive engineering is categorized (additive engineering in perovskites and at perovskite/hole transport layer interfaces) and reviewed in detail. Finally, future research directions on additive engineering are suggested for further enhancing stability and improving PCE.