Highly efficient and stable Cs4PbBr6@KBr color conversion films constructed through inkjet printing technology

All-inorganic cesium lead halide perovskite materials have potential applications in mini/micro-LED display applications due to their excellent photoelectric properties. However, these materials have an uncontrollable tendency to form large-sized crystals and poor stability, which is not conducive to miniaturized optoelectronic applications. Herein, a novel Cs4PbBr6@KBr color conversion film (Cs4PbBr6@KBr CCFs) with both excellent luminescence properties and high stability was in situ constructed by using inkjet printing technology. The improvement in performance is attributed to the reduction in perovskite defects within the structure and the isolation of oxygen and water by the surface modification layer, which is related to the higher solubility product of KBr. The Cs4PbBr6@KBr CCFs printed on a PET flexible substrate present a high-resolution dot matrix of 16.7 μm and a homogeneous and bright green emission with a high photoluminescence quantum yield of 94%. Moreover, the Cs4PbBr6@KBr CCFs retain 65% of their initial intensity after being aged at 70 °C for 16 h, which is superior to that of perovskite CCFs without the coating of KBr. These results indicate that the Cs4PbBr6@KBr composite has excellent potential in realizing mini/micro-LED displays with high resolution and anti-counterfeiting lables.