Enhanced Emission Efficiency and Stability of Blue-Emitting Quasi-2D Perovskites via Strain-Modulating Lewis Base Addition

Achieving stable and efficient blue light-emitting diodes (LEDs) based on metal halide perovskites has remained challenging due to defect-induced nonradiative recombination, halide ion migration, and phase segregation. This study demonstrates an effective strategy to enhance emission efficiency and stability in blue-emitting quasi-two-dimensional (2D) perovskite films by incorporating polyvinylpyrrolidone (PVP) as a Lewis base additive. PVP interacts strongly with A-site cations and Pb atoms, suppressing halide migration, passivating grain boundaries, and annihilating defects. Its ability to modulate stress within the perovskite layer, especially mitigating phase segregation under electrical stress, is particularly notable. As a result, the PVP-treated quasi-2D perovskite thin films exhibited a photoluminescence quantum yield of 32% and enhanced blue emission stability even at elevated temperatures. The blue LED with PVP-treated quasi-2D perovskites exhibited 6.42 times improved emission efficiency compared to the pristine one, demonstrating superior color stability with negligible electroluminescence peak shifts under high operating voltages. These improvements highlight the dual role of PVP in defect passivation and stress modulation, which significantly enhances the operational stability of the devices. While the emission efficiency remains modest, the improved color stability and extended operational lifetime achieved by PVP treatment represent a critical step toward the practical realization of stable perovskite-based blue LEDs.