Dual Polyvinylpyrrolidone Interlayer Engineering for Charge Balance and Dissolution-Suppressive Interface Stabilization in All-Solution-Processed Inverted InP Quantum Dot Light-Emitting Diodes

Herein, a dual-interface engineering strategy that introduces polyvinylpyrrolidone (PVP) interlayers at the upper and lower interfaces of the indium phosphide (InP) quantum dot (QD) emissive layer is proposed. This strategy aims to address the critical challenges of emissive layer dissolution and charge injection imbalance in all-solution-processed inverted quantum dot light-emitting diodes (QDLEDs). The PVP interlayer at the interface with the QD/hole transport layer effectively suppresses QD dissolution during subsequent solution processing, forming a stable and homogeneous emissive layer. The underlying PVP layer at the electron transport layer/QD interface modulates the electron-hole injection balance and reduces leakage current pathways. The influence of the PVP interlayers on charge transport characteristics and surface morphology was systematically investigated via single-carrier device analysis and atomic force microscopy measurements. The incorporation of PVP interlayers considerably improves the device performance, increasing the external quantum efficiency, current efficiency, and power efficiency by ∼40%, 39%, and 63%, respectively. These findings indicate that PVP-based interface control can effectively enhance the structural stability and electrical performance of inverted InP light-emitting diodes.