(A) study on highly luminescent QD film based on the adsorption between CdZnS/ZnS QDs and mesoporous $TiO_2$ template

Abstract

Quantum dots (QDs) have received great interests as a next-generation display material because of its narrow full-width half-maximum(FWHM) and size-tunable emission wavelength. Generally, QD film is fabricated by spin coating method to be served as an emission layer or color filter. However, the spin coating method severely wastes the amount of coating material in the process (over 90%). Considering the cost of Cd-based QDs, it is required to prevent dissipation of QDs in order for QDs to be applied to display industry with economical benefits. On the other hand, dipping method can be an alternative way to fabricate films with minimized waste of materials. Therefore, we synthesized mesoporous $TiO_2$ template and CdZnS/ZnS QDs capped with oleic acid(OA) to chemically adsorb the QDs into the template through dipping method. This was possible through exchanging the ligand of QDs from OA to mercaptopropionic acid (MPA). Consequently, in addition to the suppressed loss of QDs, the amount of QDs in the fabricated film increased about twofold compared to spin-coated QD film. This was because the QDs were successfully adsorbed in the pores of mesoporous $TiO_2$ template, which has various porosity. Owing to the increased amount of QDs in the template, the photoluminescence (PL) intensity of synthesized film increased by 17.2 times compared to bare QD film.