Methylammonium Cation-Regulated Controllable Preparation of CsPbBr₃ Perovskite Quantum Dots in Polystyrene Fiber with Enhanced Water and UV Light Stabilities

MABrcan limit the growth of quantum dots by modulatingthe critical Gibbs free energy of MA(+)-doped CsPbBr3 PQDs and act as part of the ligand to passivate some of thesurface defects. In situ fabrication of lead halide perovskite quantumdots (PQDs)is important for narrow-band emitters for LED displays due to thesimple work procedure and convenient usability; however, the growthof PQDs is not readily controllable in the preparation, resultingin low quantum efficiency and environmental instability of PQDs. Here,we demonstrate an effective strategy to controllably prepare CsPbBr3 PQDs in polystyrene (PS) under the regulation of methylammoniumbromide (MABr) via electrostatic spinning and thermal annealing techniques.MA(+) slowed down the growth of CsPbBr3 PQDs andacted as a surface defect passivation reagent, which was proved byGibbs free energy simulation, static fluorescence spectra, transmissionelectron microscopy, and time-resolved photoluminescence (PL) decayspectra. Among a series of prepared Cs(1-x )MA( x )PbBr(3)@PS (0 <= x <= 0.2) nanofibers, Cs(0.88)MA(0.12)PbBr(3)@PS shows the regular particle morphology of CsPbBr3 PQDs and the highest photoluminescence quantum yield of upto 39.54%. The PL intensity of Cs(0.88)MA(0.12)PbBr(3)@PS is 90% of the initial intensity after immersing in waterfor 45 days and 49% of the initial value after persistent ultraviolet(UV) irradiation for 27 days. A high color gamut containing 127% ofthe National Television Systems Committee standard with long-timeworking stability was also obtained on light-emitting diode packagemeasurements. These results demonstrate that MA(+) can effectivelycontrol the morphology, humidity, and optical stability of CsPbBr3 PQDs in the PS matrix.