Recent progress in surface modification and interfacial engineering for high-performance perovskite light-emitting diodes

Perovskite-based light-emitting diodes (PeLEDs) are an emerging lighting and display due to their extraordinarily photoelectric characteristics. In the past few years, external quantum efficiency (EQE) has enhanced from less than 0.1% to over 20%, which is comparable to that of conventional organic light-emitting diodes. As a result of low production cost and high energy efficiency of perovskite materials, PeLEDs have attracted enormous attention. However, in the cost-efficient solution-based process, the perovskite film with the occurrence of electron and hole traps as well as the rough surface are unfavorable for the PeLEDs. Surface modification and interfacial engineering play a significant role in the performance of light-emitting devices. Various strategies for the improvement of surface morphology have been executed to solve intrinsic challenges related to PeLEDs. In this review, recent advances in the morphology engineering of PeLEDs are summarized. Compositional engineering, additive engineering, annealing treatment, humidity management, solvent control, gas-quenching and vapor-assisted method, as well as interlayer engineering and self-assembly monolayer, are specifically discussed; additionally, an outlook is addressed that will provide inspiration for further enhancing the performances of PeLEDs.