Insight into Perovskite Light-Emitting Diodes Based on PVP Buffer Layer

Abstract Metal halide perovskite light-emitting diodes (PeLEDs) have shown enormous potential in the field of display. Recently, the economical and practical polyvinylpyrrolidone (PVP) has been widely used in perovskite-based optoelectronic devices. However, its comprehensive and complex effects are still lack of in-depth research. In this work, PVP interlayer is experimentally evidenced to play a multi-function role of passivating interface defects between hole transport layer (HTL) and emissive layer (EML), inhibiting grain boundary defects of EML, balancing hole/electron mobilities, and supporting as a hydrophilic interlayer to improve the wettability in PeLEDs. As a result, the hydrophobic poly-TPD HTL based 3D CsPbBr3, quasi-2D PEA2[CsPbBr3]5PbBr4 and 3D CsPb(Cl0.3Br0.7)3 PeLEDs are successfully demonstrated with the assistance of PVP buffer layer, yielding the optimized luminance, external quantum efficiency, current efficiency and T50 lifetime of 45582 cd m-2, 2.78%, 8.4 cd A-1 and 2400 s for CsPbBr3 PeLED, 14074 cd m-2, 5.50%, 17.6 cd A-1 and 7260 s for PEA2[CsPbBr3]5PbBr4 PeLED, 774 cd m-2, 0.40%, 0.47 cd A-1 and 330 s for 3D CsPb(Cl0.3Br0.7)3 PeLED, respectively. This work provides a deep insight of PVP buffer layer into various HTLs and multi-colored PeLEDs for the first time, which helps to enhance the key optoelectronic performance for PeLEDs.