Elimination of unexpected destruction on CsPbBrxI3-x nanocrystals arising from polymer matrix

Cesium lead halide perovskite (CsPbX3) nanocrystals (NCs) have exhibited promising applications in light-emitting diodes (LEDs) due to their tunable bandgap and high quantum efficiency. Backlighting LEDs based on CsPbBr3 NCs with green emission have been widely designed to show their superiority. However, unlike CsPbBr3 NCs, backlighting LEDs composed of mixed-halide perovskite (CsPbBrxI3-x) NCs have rarely been reported and should be further applied in colorful LEDs for granted, mainly because of the unexpected destructive effects from the commercial polymer matrix verified in this work. Purification of a commercial polymer matrix was promoted as an effective method to eliminate the destructive effects. Further investigation proved that the species with strong polarity and oxidability, e.g., BPO in commercial PMMA, are responsible for such destructive effects by inducing the structural transformation of CsPbBrxI3-x NCs. We believe such results can help to gain a deeper understanding of the degradation mechanism of mixed-halide perovskite materials and indicate a promising method to develop stable colorful perovskite-based LEDs.