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All‐inorganic CsPbX3 (X = I, Br, Cl or their mixtures) perovskites attract enormous attention in recent years due to their excellent optoelectronic properties, outstanding thermal/light stability, and wide range of applications in electronic devices. Encouragingly, the reported power conversion efficiency of CsPbX3 perovskite solar cells (PSCs) rockets up from 2.9% in 2015 to the present 21.0%. In order to further promote the performance of CsPbX3 PSCs toward the Shockley–Queisser efficiency limit, it is important to optimize the quality of perovskite films by crystallization kinetics modulation and defect suppression. In this review, first, some fundamental information about all‐inorganic CsPbX3 perovskites is briefly introduced, including the crystallization mechanism, growth mode, crystal structure, and phase stability as well as possible defects and their effects on device performance. Second, the recent exciting progress of the crystallization modulation strategies for high‐quality CsPbX3 films is summarized and discussed in detail. The advantages of different strategies, including annealing engineering, solvent engineering, precursor engineering, composition engineering, and interface engineering, are highlighted. Finally, methods for improving the efficiency of inorganic PSCs are discussed, and the future development prospects of inorganic PSCs are also outlined. [ABSTRACT FROM AUTHOR]

Surmounting complicated defects at the electron transport layer (ETL) and perovskite interface plays a non‐trivial role in improving efficiency and stability of perovskite solar cells (PSCs). Herein, an asymmetric interface modification strategy (AIMS) is developed to passivate the defects from both a SnO2 ETL and the perovskite buried surface via incorporating 1,3‐thiazole‐2,4‐diammonium (TDA) into the SnO2/perovskite interface. Detailed experimental and calculated results demonstrate that N3 (the nitrogen atom bonding to the imine) in the TDA preferentially cures the free hydroxyl (OH), oxygen vacancy (VO), and the Sn‐related defects on the SnO2 surface, while N1 (the nitrogen atom bonding to the vinyl) is more inclined to passivate the Pb2+ and I− related defects at the perovskite buried surface. As a result, the TDA‐modified FACsPbI3 PSC yields a champion power conversion efficiency (PCE) of 24.96% with a gratifying open‐circuit voltage (Voc) of 1.20 V. In addition, the optimized PSCs exhibit charming air‐operational stability with the unencapsulated device sustaining 97.04% of its initial PCE after storage in air conditions for 1400 h. The encapsulated device maintains 90.21% of its initial PCE after maximum power point tracking for 500 h. [ABSTRACT FROM AUTHOR]

Formamidinium methylammonium lead iodide (FAMAPbI3) perovskite has been intensively investigated as a potential photovoltaic material because it has higher phase stability than its pure FAPbI3 perovskite counterpart. However, its power conversion efficiency (PCE) is significantly inferior due to its high density of surface detects and mismatched energy level with electrodes. Herein, a bifunctional passivator, methyl haloacetate (methyl chloroacetate, (MClA), methyl bromoacetate (MBrA)), is designed to reduce defect density, to tune the energy levels and to improve interfacial charge extraction in the FAMAPbI3 perovskite cell by synergistic passivation of both CO groups and halogen anions. As predicted by modeling undercoordinated Pb2+, the MBrA shows a very strong interaction with Pb2+ by forming a dimer complex ([C6H10Br2O4Pb]2+), which effectively reduces the defect density of the perovskite and suppresses non‐radiative recombination. Meanwhile, the Br− in MBrA passivates iodine‐deficient defects. Consequently, the MBrA‐modified device presents an excellent PCE of 24.29%, an open‐circuit voltage (Voc) of 1.18 V (Voc loss ≈ 0.38 V), which is one of the highest PCEs among all FAMAPbI3‐based perovskite solar cells reported to date. Furthermore, the MBrA‐modified devices without any encapsulation exhibit remarkable long‐term stability with only 9% of PCE loss after exposure to ambient air for 1440 h. [ABSTRACT FROM AUTHOR]

Inorganic CsPbI2Br perovskite is promising for solar cell applications due to its excellent thermal stability and optoelectronic characteristics. Unfortunately, the current high‐efficiency CsPbI2Br perovskite solar cells (PSCs) are mostly fabricated in an inert atmosphere due to their instability to moisture. Herein, a low‐dimensional intermediate‐assisted growth (LDIAG) method is reported for the deposition of CsPbI2Br film in ambient atmosphere by introducing imidazole halide (IMX: IMI and IMBr) into the precursor solution to control both nucleation and growth kinetics. The IMX first combines with PbI2 in the precursor film to form a 2D intermediate which then gradually releases PbI2 to slowly form high‐quality CsPbI2Br film during annealing. It is found that the LDIAG method produces a uniform, highly crystalline, pinhole‐free, and stable CsPbI2Br film with low defect density. Consequently, the solar cell efficiency is increased to as high as 17.26%, one of the highest for this type of device. Furthermore, the bare device without any encapsulation shows excellent long‐term stability with ≈86% of its initial efficiency retained after being exposed to the ambient environment for 1000 h. This work provides a perspective to tune the intermediate phases and crystallization pathway for high‐performance inorganic PSCs formed under ambient conditions. [ABSTRACT FROM AUTHOR]