The performance of perovskite light-emitting diodes (PeLEDs) has been drastically improved recently. Therein, the coexistence of polydisperse perovskite domains has been one worthy subject of study. The crystallization of perovskite is affected by the buried interface character with the bottom contact layer; and the trap states also inherently exist at the buried interface of the perovskite film, which induce the nonradiative recombination and impede the PeLED performance. In this work, we focus on the crystallization modulation of monodisperse perovskite nanodomains toward high-performance PeLEDs. We show that a LiBr pre-modification layer on the bottom substrate induces the formation of monodisperse perovskite phase. In this system, the carrier transferring process deriving from the polydisperse phases is reduced. In addition, the LiBr pre-modification layer at the buried interface minimizes the trap states and enhances the radiative recombination of perovskites. Accordingly, our PeLEDs show a champion external quantum efficiency (EQE) of 25.5% for 4 mm² device, and 22.9% for 100 mm² device.

Perovskite light-emitting diodes (PeLEDs) rely on optimized device architecture to realize effective electro-optical converting. Especially, the stacks of dissimilar semiconducting materials form heterointerfaces, at which the defects and energetics of perovskite film greatly affect the device performance. Herein, we focus on the heterointerface engineering of perovskite towards high-quality PeLEDs. The defect engineering at both the bottom-surface (namely buried interface) and top-surface of perovskite film is simultaneously performed by semiconducting passivating molecules, which feature aligned energy levels and superior carrier injection ability regarding to perovskite. Moreover, such defect passivation could influence the heterointerface energetics. The perovskite work function is decreased by our suggested passivator treatment because of interface dipole, which results in band bending at the heterojunction and modulates the carrier dynamics. Hence, the electron injection is greatly enhanced, which boosts the up-conversion electroluminescence in current system. Overall, via the heterointerface engineering of defects and energetics synergistically, efficient PeLEDs with 3-fold enhancement of external quantum efficiency and low driving voltages with respect to pristine ones are achieved based on our proposed PeLED architecture.