Methylammonium Cation-Regulated Controllable Preparation of CsPbBr₃ Perovskite Quantum Dots in Polystyrene Fiber with...

In situ fabrication of lead halide perovskite quantum dots (PQDs) is important for narrow-band emitters for LED displays due to the simple work procedure and convenient usability; however, the growth of PQDs is not readily controllable in the preparation, resulting in 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 methylammonium bromide (MABr) via electrostatic spinning and thermal annealing techniques. MA⁺ slowed down the growth of CsPbBr₃ PQDs and acted as a surface defect passivation reagent, which was proved by Gibbs free energy simulation, static fluorescence spectra, transmission electron microscopy, and time-resolved photoluminescence (PL) decay spectra. Among a series of prepared Cs_1-MAPbBr₃@PS (0 ≤ x ≤ 0.2) nanofibers, Cs_0.88MA_0.12PbBr₃@PS shows the regular particle morphology of CsPbBr₃ PQDs and the highest photoluminescence quantum yield of up to 39.54%. The PL intensity of Cs_0.88MA_0.12PbBr₃@PS is 90% of the initial intensity after immersing in water for 45 days and 49% of the initial value after persistent ultraviolet (UV) irradiation for 27 days. A high color gamut containing 127% of the National Television Systems Committee standard with long-time working stability was also obtained on light-emitting diode package measurements. These results demonstrate that MA⁺ can effectively control the morphology, humidity, and optical stability of CsPbBr₃ PQDs in the PS matrix.