Synthesis and spectroscopic characterization of CsPbBr₃/Cs₄PbBr₆ perovskites synthesized via the microwave-assisted heating process for backlight display devices

In this study, CsPbBr₃/Cs₄PbBr₆ composites were prepared via microwave-assisted (MA) and conventional heating (CH) routes. X-ray diffraction and high-resolution transmission electron microscopy confirmed the coexistence of CsPbBr₃ and Cs₄PbBr₆ phases in the prepared samples. The steady-state absorption spectra of the synthesized perovskites exhibited excitonic peaks at 310 and 525 nm because of the absorption of Cs₄PbBr₆ and CsPbBr₃, respectively. The prepared samples exhibited characteristic emission peaks at approximately 523 nm. The MA-derived sample exhibited high color purity (94%), high quantum yield (89%), and good thermal stability (>98% after 100 h of treatment). By contrast, the CH-derived sample exhibited low color purity (91%) and quantum yield (70%). Furthermore, microwave irradiation with polar molecules in MA heating resulted in the rapid generation of homogeneous heat within the heated materials, which induced the substantial nucleation and growth of CsPbBr₃. This phenomenon enhanced intensity of photoluminescence emission. The MA-derived sample exhibited a shorter excitonic lifetime (20 ns) than the CH-derived sample did (32 ns) because the MA-derived sample had less nonradiative trap sites. The color gamut of the as-prepared light-emitting devices fabricated with the MA-derived sample was 125% of the NTSC. This study indicated that the incorporation of microwave heating in the synthesis process is an effective approach for preparing CsPbBr₃/Cs₄PbBr₆ composites with a wide color gamut, good thermal stability, and a PLQY.