Double-passivated MAPbBr3 nanocrystals with nitrogen-doped graphene quantum dots and polyvinylidene fluoride for white light LEDs

This study addresses the challenge of synthesizing highly emissive and stable MAPbBr 3 nanocrystals (NCs) for practical device applications. A double-passivation approach was developed through using nitrogen-doped graphene quantum dots (NGQDs) and polyvinylidene fluoride (PVDF) during the in-situ synthesis of MAPbBr 3 NCs. By optimizing the amount of NGQDs, the resulting MAPbBr 3 /PVDF/NGQDs composite films exhibited green emission at 522 nm with a narrow spectral width of 17.7 nm. The films demonstrated exceptional stability, retaining 60 % of their initial photoluminescence (PL) intensity after 144 h of water immersion and 96 % of their initial intensity after 10 min of heating at 100 °C. This stability is attributed to the NGQDs reducing defects and acting as nitrogen-enhanced sites that promote consistent crystal formation. Additionally, the composite film was used to fabricate a white light-emitting diode (WLED) with a color gamut coverage rate of 125 % under the National Television Standards Committee (NTSC) standard and 93.8 % under the Rec.2020 standard. This work might present a synergistic strategy combining in-situ defect passivation with encapsulation, offering a viable solution to the stability-efficiency trade-off in perovskite NCs and advancing high-color-gamut flexible displays.