Enhanced Photostability in Aqueous-Prepared MAPbBr₃@polymer Films through Ligand-Regulated Exciton Binding Energy and Radiative Recombination

Perovskite nanocrystals (PNCs) in polymer matrices, despite moisture and oxygen protection, suffer photostability issues under blue light, hindering their commercial use in lighting and displays. Herein, we introduce <i>N</i>-Oxalylglycine (NOG), a short-chain ligand with a strongly binding dual-site structure, to control MAPbBr₃ PNCs growth in polymer matrices. Our results reveal that incorporating NOG ligands boosts the exciton binding energy and accelerates the radiative recombination rate in MAPbBr₃ PNCs, which mitigates light-induced degradation caused by charge accumulation. As a result, the NOG-modified MAPbBr₃ PNCs@ poly(vinyl alcohol) (PVA) film achieves a photoluminescence quantum yield (PLQY) of 96%, and a narrow full-width at half-maximum (FWHM) of 25 nm. Notably, the PLQY remains stable even after 1444 h of uninterrupted blue light exposure (460 nm, 13 mW·cm^-2). The as-assembled white light emitting diodes (WLEDs) device achieves an exceptional luminous efficacy of 96.03 lm·W^-1 and a wide color gamut extending to 126% of the National Television System Committee (NTSC) standard. Moreover, the device exhibits excellent operational stability, retaining over 90% of its initial high brightness of 20,000 cd·m^-2 after 168 h of continuous operation. These findings offer valuable insights into improving the photostability of PNCs, holding great promise for their application in high-performance backlight devices.