Temperature-dependent steady-state and time-resolved photoluminescence spectroscopy of CsPbBr3 encapsulated with PbBrOH and PVA

In this work, photoluminescence (PL) intensity and stability of CsPbBr3/PbBrOH powders synthesized by one-pot method are enhanced through the encapsulation of poly (vinyl acetate) (PVA) in water. Understanding the function of PbBrOH and PVA matrix for photogenerated transition can be achieved through temperature-dependent steady-state and time-resolved PL. The enhanced PL quantum yield (65.9%) and longer lifetime indicate the strengthened structural stability and a significant reduction in nonradiative recombination of CsPbBr3. Negative thermal quenching can be observed and interpreted using a multilevel PL transition model. Through nanosecond time-resolved PL spectra under femtosecond laser excitation, it is revealed that the PL position shows a redshift (∼8 nm) with time delay due to the reduction of band-filling effect during the recombination of photoexcited carriers. PVA further encapsulates CsPbBr3/PbBrOH powders to form a flexible film, which exhibits excellent thermal and water stability due to the dual protective effects of PVA and PbBrOH. The experimental investigation demonstrates that CsPbBr3 encapsulated by PbBrOH and PVA possesses excellent luminescent and water-resistant characteristics, making it a new choice for practical applications in LEDs and screen printing.