Ultrathin, Friendly Environmental, and Flexible CsPb(Cl/Br)3-Silica Composite Film for Blue-Light-Emitting Diodes

Due to intrinsic defects in blue-light-emitting perovskite materials, the charge carriers are prone to being trapped by the trap states. Therefore, the preparation of efficient blue-light-emitting perovskite materials remains a significant challenge. Herein, CsPb(Cl/Br)3 nanocrystal (NCs)@SiO2 structures were fabricated through hydrolyzing (3-aminopropyl)-triethoxysilane (APTS). SiO2 can passivate the surface trap states of NCs, suppress the nonradiative recombination pathways of NCs, and effectively stabilize the surface of NCs. CsPb(Cl/Br)3 NCs@SiO2 exhibits higher photoluminescence (PL) intensity and lifetime compared to those of the pure CsPb(Cl/Br)3 NCs. The enhancement of the exciton binding energy (Eb) leads to increased PL intensity and lifetime in CsPb(Cl/Br)3 NCs @SiO2, as demonstrated by temperature-dependent PL spectra. Subsequently, a 0.3 mm film of CsPb(Cl/Br)3 NCs@SiO2/poly(methyl methacrylate) (PMMA) was fabricated through optimizing the casting method. Due to the effective protection provided by SiO2 and PMMA, CsPb(Cl/Br)3 NCs@SiO2/PMMA film exhibits excellent thermal, water, and air stability. Moreover, the CsPb(Cl/Br)3 NCs@SiO2/PMMA film also exhibits good flexibility, maintaining the PL intensity unchanged under bending conditions. Importantly, lead can be well encapsulated in SiO2 and PMMA, effectively preventing lead from leaking into the environment. This research demonstrates the potential of a CsPb(Cl/Br)3 NCs@SiO2/PMMA film for applications in the friendly environmental field of optoelectronics, including light-emitting diodes (LEDs) and flexible displays.