Surface engineering towards highly efficient perovskite light-emitting diodes

Perovskite light-emitting diodes (PeLEDs) have been intensively researched in recent years, and their rapid evolution of efficiency has resulted in their becoming a member of the family of devices with external quantum efficiencies (EQEs) > 20%. In this evolution process, surface engineering was found to be a key factor for obtaining the high-efficiency PeLEDs because of its effects on the state and the density of charge carriers, the density of defects, the transport and the injection of charge, etc. In this review, we mainly focus on recent works on highly efficient PeLEDs based on perovskite 3D/quasi-2D/quantum dots and try to discover the reasons behind their high performance. With continuous optimization of materials and devices, especially with surface engineering, the efficiency of PeLEDs is expected to continue growing and to reach an exciting new level in the near future.