Identifying, Understanding and Controlling Defects and Traps in Halide Perovskites for Optoelectronic Devices: A Review

In the past decade, halide perovskite materials have captivated a great deal of attention for the application in optoelectronic devices. To realize the commercialization of optoelectronic devices made from this exhilarating material system, in particular to boost the efficiency and the stability, the formation mechanisms of defects, their impact on device performance and lifetime and the way to overcome them must be thoroughly investigated. In this review, the current understanding of the defect creation mechanism in as-synthesized and environment-exposed samples will be presented. The defect induced phenomenon and their impact on the material properties and device performances will be explained. The various defect characterization techniques will be summarized regarding their working principles and limitations. The defect engineering including both physical and chemical methods will be discussed in detail. We believe that although there are still unsolved puzzles in the field, the research on the defect mechanism and engineering is of great significance in making halide perovskites into real applications.