Defect Behaviors in Perovskite Light-Emitting Diodes

Defects play a pivotal role in the physical and chemical properties of semiconductor materials. Regulation of the type, distribution, and quantity of defects within the crystal allows for refinement of material properties, which, in turn, affects the performance of semiconductor devices. Looking back at the development in the realm of perovskite, the research on defect behaviors has always been closely linked to the outstanding improvements in solar cells, light-emitting diodes (LEDs), and other devices. Recently, the external quantum efficiencies (EQEs) of red, green, and blue perovskite LEDs have approached the efficiency limit after comprehensive defect suppression strategies. The research emphasis on perovskite LEDs has gradually shifted from efficiency improvement to stability improvement, as well as defect formation and passivation mechanisms. However, existing views on the origin and action of defects are contradictory. In this Review, we focus on the origins and negative effects of defects from the perspective of LEDs performance; we also summarize the defect passivation strategies developed in recent studies. Given the universality of defects, a cogent summary of defect behaviors may help to further improve the performance of perovskite LEDs and promote the development of other optoelectronic devices.