Researchers from the Beijing Institute of Technology and MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices have developed perovskite quantum dots microarrays with strong potential for quantum dots color conversion (QDCC) applications, including photonics integration, micro-LEDs, and near-field displays.
QDCC is considered a versatile way to achieve full-color organic light-emitting diodes and micro-light-emitting diodes displays. QDCC provides a wide range of color performance and easy integration. However, conventional QDCC pixels, fabricated by the commonly used method of inkjet printing, tend to be too thin to achieve efficient color conversion. The conventional combination of quantum dots and coffee-ring effects or puddle of particle-laden liquid that occur after evaporation, lowers the light conversion efficiency and emission uniformity in quantum dot microarrays. This also contributes to blue-light leakage or optical crosstalk, where unwanted coupling occurs between signal paths.
Perovskite quantum dots (PQDs) hold potential as an attractive material and can resolve some of the problems found in conventional QDCC. While perovskite quantum dots are relatively new, they have already been shown to have attractive properties that make them extremely suited for electronic and optoelectronic applications. By using patterned black photoresist molds to make the QDs pixels, researchers have been able to increase the pixel thickness and avoid the optical crosstalk, a common but significant issue which prevents better printing results. But the manufacturing costs increased substantially. The research team set out to resolve these challenges by developing a method that creates PQDs with a robust 3D structure.
“To solve these problems, we fabricated 3D perovskite quantum dots microarrays by combining the inkjet printing and in-situ fabrication of perovskite quantum dots during the photopolymerization of precursor ink,” said Gaoling Yang, an assistant professor in the School of Optics and Photonics at Beijing Institute of Technology. Photopolymerization is a technique that uses light to create a polymer structure. Using the photopolymerization technique, the researchers achieved a perovskite quantum dots color conversion microarray with a pixel size of 20 microns. Their technique provides a new technical route for light conversion applications, such as color conversion micro-LED.
The fabricated PQDs microarrays reportedly exhibit characteristics that are desirable for QDCC applications, including 3D morphology with hemisphere shape and strong photoluminescence. These microarrays achieved strong and uniform photoluminescence in large area because of the seamless integration with in situ-fabricated PQDs. The researchers’ technique demonstrated the potential use of the in situ direct print photopolymerization method for fabricating patterned multicolor perovskite quantum dots microarrays with both wide color gamut and high resolution.
The researchers’ results further confirm the realization of high-quality multicolor microarrays through the inkject printing approach. The team sees potential applications for their work: “The in situ direct print photopolymerization technique allows for precise control of the pixel structure, removing the aggregation of QDs and coffee-ring effects in microarrays, which will aid in their expansion in photonics integration, full-color display, on-chip biomedical diagnostics, and next-generation augmented reality and virtual reality devices,” said Yang.
