Tunable CsPb(Br/Cl)3 perovskite nanocrystals and further advancement in designing light emitting fiber membranes

Abstract

Cesium lead halide perovskite nanocrystals (NCs) have drawn a great deal of interest in optoelectronic and photonic applications due to their intrinsic and attractive photoluminescence properties, though, their commercial viability is of concern due to their intrinsic instability. In this study, blue and green luminous PMMA–CsPbX₃ (X = Cl/Br) fibers were fabricated via the Forcespinning technique, where the polymer matrix encapsulated the NCs. Blue CsPbX₃ NCs (b-CPX NCs) were synthesized under ambient conditions while fine color tuned blue to green CsPbX₃ NCs (g-CPX NCs) were obtained after heat treatment at 150 °C. Field emission scanning electron microscopy (FESEM) shows fibers with diameters in the single digit microscale. Efficient encapsulation of NCs in the PMMA fiber was confirmed using FTIR spectroscopy. UV visible spectra of the NCs suggested a quantum confinement effect. Pristine NCs show bright blue and green emission from b-CPX and g-CPX NCs under UV irradiation (365 nm) which was successfully reproduced even upon encapsulation in the PMMA matrix. In both cases, the PMMA matrix besides promoting QD encapsulation also enhanced the photoluminescence quantum yield (PLQY) from 25.5% to 31.1% (blue PMMA fibers) and 42.6% to 51.4% (green PMMA fibers) compared to bare NC PLQY. PMMA–CsPbX₃ (X = Cl/Br) also possessed narrow half-peak width compared to pristine NCs suggesting high color purity. This work provides a novel polymer fiber-based encapsulation approach to solve the intrinsic instability issues of CsPbX₃ NCs, therefore prompting promising practical applications.