Hisamitsu Takahashi

21.2: Transparent Thin Film Desiccant for OLEDs

A transparent thin film desiccant capable of improving the storage reliability of OLED was developed, which was named OleDry. OleDry is an excellent desiccant mainly composed of aluminum complex, which well dissolves in hydrocarbon solvent. Taking advantage of the dissolubility of aluminum complex, transparent thin film can be formed by coating OleDry on the inner surface of the cover glass and drying it. Not only to the standard OLEDs, a thin transparent OLED, a top-emission OLED and even a flexible OLED using resin substrate are viable with high storage reliability by the use of OleDry.

Glycothermal Synthesis of ZnGa2O4 : Mn2 + Nanophosphor and Change in Its Photoluminescence Intensity by Heat-Treatment

ZnGa 2 O 4 :Mn 2+ nanophosphors were synthesized from zinc acetate dihydrate, gallium acetylacetonate, and manganese(II) acetate tetrahydrate in 1,4-butanediol by glycothermal method at 300°C for 2 h. Their average particle diameter was 12.1 ± 2.5 nm. We investigated the influence of temperatures of postheat-treatment in Ar on the luminescent and structural properties. The photoluminescence (PL) intensity slightly decreased after heating below 900°C. The PL intensity increased between 900 and 1200°C, reached at the maximum at 1200°C and decreased over 1200°C. The decrease of the PL intensity by heating below 900°C occurred by the removal of adsorbed organic species. The X-ray diffraction profile indicated the decomposition of ZnGa 2 O 4 to Ga 2 O 3 and ZnO by heating over 1200°C, resulting in the decrease of the PL intensity. The change in the integrated intensity of electron paramagnetic resonance due to paramagnetic Mn 2+ with the temperature of heat-treatment in Ar was similar to that of the PL intensity. This suggests that the PL intensity is correlated to the incorporated Mn 2+ amount.

Kinetic Analysis on the Photoluminescence Enhancement of 3-Mercaptopropyl Trimethoxysilane-Modified ZnS:Mn2+ Nanocrystal Colloidal Solution by Aging Effect

The ZnS:Mn2+ nanocrystal colloidal solution is prepared by the in situ surface modification co-precipitation method in the presence of 3-mercaptopropyl trimethoxysilane (MPS). The increase in the fractional photoluminescence (PL) intensity by the aging of this solution is represented as a first-order reaction. Judging from the small activation energy, we conclude that Mn2+ ions are exchanged with Zn2+ ions at the surface of ZnS nanocrystals during aging to increase the PL intensity.