Thermally stable red and green light-emitting nanohybrids are introduced as an organic luminescent converter with broad color tunability and a high color rendering index for white light-emitting diodes (LEDs). Nanohybrid-based white LEDs are thermally stable and the color coordination is not changed by heat exposure.

Fluorinated hybrid materials were synthesized for a solution-processable gate insulator. The surface energy was modified by perfluoroalkyl chains contained in the hybrid gate insulator itself. We investigated the initial morphology and growth mode of pentacene and the characteristics of organic thin-film transistors ͑OTFTs͒ to determine how these characteristics depend on the surface energy. Pentacene growth was changed from a layer-by-layer mode to a three-dimensional ͑3D͒ island growth mode at low surface energy. Tightly and uniformly grown pentacene grains at 3D island mode induced good OTFT performance, but the carrier mobility was degraded at very low surface energy due to the large amount of grain boundaries.Organic thin-film transistors ͑OTFTs͒ attract great interest due to their ease of processing, low cost, and wide applicability. The characteristics of OTFTs are very dependent on the gate insulators because the majority of the charge carriers in the OTFTs are located close to the interface between the gate insulator and the organic semiconductor. 1-3 The surface energy of the gate insulator has an effect on the initial growth behavior, the morphology, and the crystallinity of the pentacene layer; these are critical performance factors for OTFTs. The hydrophobic surface of the gate insulator, which induces the pentacene crystallinity and the interconnection between pentacene grains, enhances OTFT performance. To this end, surface treatments on the gate insulator using hexamethyldisilazane, octadecyltrichlorosilane, and other self-assembled monolayers ͑SAMs͒ were employed. [4][5][6] In this study, we considered methacrylate siloxane hybrid materials ͑hybrimers͒ simply synthesized by a sol-gel process of organoalkoxysilane. The perfluoroalkyl chain was introduced in the design of the hybrimer to tune the surface energy of the gate insulator. Instead of using an additional surface treatment on the gate insulators, we added long perfluoroalkyl chains to the hybrimer gate insulator. These chains were concentrated on the insulator surface, leading to better growth of the pentacene. We added various amounts of perfluoroalkylsilane to the hybrimer to control the surface energy of the gate insulator. Next we observed the growth behavior of the pentacene on the hybrimer gate insulator. We investigated the electrical characteristics of the fabricated OTFT to determine how these characteristics depend on the content of perfluoroalkyl chains. ExperimentalWe synthesized fluorinated hybrid materials ͑hybrimers͒ via a sol-gel process using 3-͑trimethoxysilyl͒propyl methacrylate, titanium͑IV͒ butoxide, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane ͑PFAS͒. Instead of using an additional surface treatment, we added long perfluoroalkyl chains to the hybrimer gate insulator itself. These chains were concentrated on the insulator surface, leading to better growth of the pentacene. To control the surface energy of the gate insulator, the amounts of PFAS, which contained the hydrophobic perfluoroalkyl chain, were adjusted as f...

No abstract

Cycloaliphatic epoxy hybrimer bulk was successfully fabricated by thermal curing of cycloaliphatic epoxy oligosiloxane resin synthesized by a sol-gel condensation reaction with methylhexahydrophthalic anhydride (MHHPA) and tetrabutylphosphonium methanesulfonate (TBPM). The composition of MHHPA and TBPM in the resin was optimized to minimize yellowness of the cycloaliphatic epoxy hybrimer bulk. The sample with the optimized composition showed little discoloration upon thermal aging at 120 C for 360 h under an air atmosphere. On the basis of its high thermal stability with appropriate hardness and a high refractive index of 1.55, cycloaliphatic epoxy hybrimer bulk can be used as a LED encapsulant for white LEDs.

The excellent contrast ratio, visibility, and advantages in producing thin and light displays let organic light emitting diodes change the paradigm of the display industry. To improve future display technologies, higher electroluminescence efficiency is needed. Herein, the detailed study of the non-radiative decay mechanism employing density functional theory calculations is carried out and a simple, general strategy for the design of the ancillary ligand is formulated. It is shown that steric bulk properly directed towards the phenylisoquinoline ligands can significantly reduce the non-radiative decay rate.