Defect Behaviors in Perovskite Light-Emitting Diodes

Abstract

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.

Improving anion-exchange efficiency and spectrum stability of perovskite quantum dots via an Al3+ bonding-doping synergistic effect

“…Surface defects may facilitate the anion exchange process. 32,33 With the assistance of the DDAC ligand, Cl exchanges with halogens in the [Pb-Br 6 ] 4− octahedron to form [Pb-(Br/Cl) 6 ] 4− (Fig. 1a).…”

3D and 2D Metal Halide Perovskites for Blue Light-Emitting Diodes

“…The electrons and holes injected from the cathode and anode under the electric field are transported through the hole transport layer (HTL) and electron transport layer and then confined in MHP EMLs to form excitons before light emission. Moreover, device characteristics, such as current efficiency, external quantum efficiency (EQE), and brightness, are highly dependent on the radiative recombination rate originating from the quality of the MHP thin films because the MHPs have defects, such as halide vacancies and grain boundaries, which act as charge trapping sites during device operation [40,41]. Kumawat et al reported the first blue PeLED using Br-Cl mixed-halide perovskite as emitting layers (EMLs) [37].…”

Red Perovskite Light‐Emitting Diodes: Recent Advances and Perspectives

“…[2,8,9] In addition, MHPs significantly decrease both the economic and energetic costs of film manufacturing owing to their cost-effectiveness and low-temperature solution processability. [10] The first room-temperature PeLEDs were reported in 2014 with low external quantum efficiencies (EQEs) of 0.76% due to the relatively poor morphology of the film and the large number of traps assisted by radiation-free composite. [11] With the rapid development of morphology control, composition engineering, and device engineering, tremendous improvements have been witnessed in the EQE of primary-color PeLEDs.…”