Stability enhancement and patterning of quantum dots/siloxane composites for display applications

Abstract

Conventional liquid crystal displays have realized colors using blue light, yellow phosphors, and red and green color-filters (CFs). However, the yellow light, emitted through phosphors, causes energy loss due to poor suitability between the broad yellow emission and R, G color-filters. Currently, researchers have actively incorporated quantum dots (QDs) into existing display in order to enhance energy efficiency and color-gamut. Despite that QDs are novel optical materials having narrow emission band, size-dependent emission, and high photoluminescence quantum yield, aggregation problems, when dispersing high concentration in resin, and vulnerability against heat, moisture, and chemicals are limits to apply QDs in displays. In this thesis, I developed the stability of QDs under harsh heat and moisture conditions with two-step encapsulation for long-term operating QDs-embedded films

sol-gel derived silica and organic-inorganic hybrid materials. Also, by ligand exchange and secondary thiol monomers, photo-patternable QDs/siloxane inks were synthesized. Finally, I propose a thermally stable and PL-enhanced microlens array-integrated QD/siloxane film by UV imprinting on the film surface. Compared to neat QD-film, the thickness of the microlens/QD-film decreased by 25% to realize white PL, resulting in less QD usage. I applied the high performance QDs/siloxane composites to fabricate white QD-LEDs, QD-films, and QD-CFs to confirm the high potential for various display applications.