Synthesis of SiO2-coated perovskite quantum dots for micro-LED display applications

Cadmium quantum dots (QDs) have good luminous properties, but cadmium is toxic. So, cadmium-free perovskite QDs were synthesized by chemical solution methods, realizing the new structure of the green CsPbBr3/Cs4PbBr6 perovskite QDs. The SiO2 layer passivated the perovskite QDs by the sol-gel method and hydrolysis of tetramethoxysilane (TMOS) and then dispersed in a polar solvent to facilitate mixing with negative photoresist (SU8-3010) to ensure their luminous properties are not affected by moisture and oxygen. Afterward, perovskite QDs were exposed and developed on the glass substrate by a photolithography process. The pixels were spaced apart through the black matrix to reduce the crosstalk between each other. Applying the pixelated perovskite QDs to the blue light micro-light-emitting diodes (LED) display as the color conversion layer showed that excessive blue light could penetrate through the green pixels, decreasing color purity. Therefore, we used a 23-layer distributed Bragg reflector (DBR) to reflect excess blue light on pixels back to perovskite QDs. DBR did not filter the green light, and the actual luminous intensity of green light increased by 118%, and the transmittance of blue light was only 0.5%. Finally, the alignment attaching of the graph pixelated perovskite QDs on a glass substrate to the blue light display realized monochrome/area color and full-color micro-LED display.