Multiple-cation lead mixed-halide perovskites (MLMPs) have been recognized as ideal candidates in perovskite solar cells in terms of high efficiency and stability due to decreased open-circuit voltage loss and suppressed yellow phase formation. However, they still suffer from an unsatisfactory long-term moisture stability. In this study, phosphorus-containing Lewis acid and base molecules are employed to improve device efficiency and stability based on their multifunction including recombination reduction, phase segregation suppression, and moisture resistance. The strong fluorine-containing Lewis acid treatment can achieve a champion PCE of 22.02%. Unencapsulated and encapsulated devices retain 63% and 80% of the initial efficiency after 14 days of aging under 75% and 85% relative humidity, respectively. The better passivation of Lewis acid implies more halide defects than Pb defects at the MLMP surface. This unbalanced defect type results from phase segregation that is the synergistic effect of Cs and halide ion migrations. Identifying defect type based on different passivation effects is beneficial to not only choose suitable passivators to boost the efficiency and slow down the moisture degradation of MLMP solar cells, but also to understand the mechanism of defect-assisted moisture degradation.

Recent years have witnessed continuous progress in metal halide perovskite (MHP) solar cells with a certified power conversion efficiency (PCE) exceeding 22%. However, the commercialization of MHP solar cells continues to encounter various challenges including stabilization, scalability and repeatability. Of all problems related to MHP materials, interface recombination is the most prominent, resulting in severe PCE loss within a short time. Fortunately, interface engineering has been identified as an efficient means of achieving better energy‐level alignment, reduced charge recombination, trap passivation, elimination of photocurrent hysteresis, and enhanced long‐term device stability. This review examines the relationship between specific interface modification layers and their roles in interface engineering based on device physics, revealed by several characterization methods. The latest research advances in interface modification layers according to their roles and properties are also summarized.

Large-area film deposition and high material utilization ratio are the crucial factors for large-scale application of perovskite optoelectronics. Recently, all-inorganic halide perovskite CsPbBr has attracted great attention because of its high phase stability, thermal stability, and photostability. However, most reported perovskite devices were fabricated by spin-coating, suffering from a low material utilization ratio of 1% and a small coverage area. Here, we developed a spray-coating technique to fabricate a CsPbBr quantum dot (QD) film photodiode which had a high material utilization ratio of 32% and a deposition rate of 9 nm/s. The film growth process was studied, and substrate temperature and spray time were two key factors for the deposition of uniform and crack-free QD films. The spray-coated photodiode was demonstrated to be more suitable for working in the photodetector mode because a low dark current density of 4 × 10 mA cm resulting from an extremely low recombination current contributed to a high detectivity of 1 × 10 Jones. A high responsivity of 3 A W was obtained at -0.7 V under 365 nm illumination, resulting from a low charge-transfer resistance and a high charge recombination resistance. We believe that the spray deposition technique will benefit the fabrication of perovskite QD film optoelectronics on a large scale.

Among the leading energy materials, metal tri-halide perovskite quantum dots (PQDs) with outstanding optoelectronic properties are at the forefront of current research.

Flexible all-inorganic perovskite/hole-conducting layer heterostructure photoconductors with excellent stability have been fabricated. The enhanced photoresponse results from the interfacial charge transfer from perovskite to conducting layer.