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...

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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.

Cycloaliphatic epoxy oligosiloxane resins with a high degree of condensation (>85%) were synthesized by a nonhydrolytic sol–gel reaction using 2‐(3,4‐epoxycyclohexyl)ethyltrimethoxysilane (ECTS), diphenylsilanediol (DPSD), and triphenylsilanol (TPS). Cycloaliphatic epoxy hybrimers with 2 mm thickness fabricated by thermal curing of cycloaliphatic epoxy oligosiloxane resins with a hardener and catalyst were optically transparent (∼90%) with a high refractive index of up to 1.583. The fabricated hybrimers also show high thermal resistance having no yellowing during thermal aging at 120°C for 1008 h and a high decomposition temperature (>300°C). On the strengths of these characteristics, the hybrimers are expected to find application as LED encapsulants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

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.

A highly condensed epoxy-oligosiloxane resin was synthesized using a sol-gel condensation reaction of (3-glycidoxypropyl)trimethoxysilane and diphenylsilanediol in the presence of solvent. A higher degree of condensation and a larger molecular size of oligosiloxanes were achieved compared to a condensation reaction without the addition of a solvent. The epoxy-hybrimer coating film was fabricated by the spin coating and thermal curing of the synthesized oligosiloxane resin. The leakage current density and the dielectric constant decreased from 25.9 to 7.6 nA cm(-2) and from 3.16 to 3.03, respectively, by using the solvent in the preparation. The hybrimer coating film of a highly condensed oligosiloxane resin had a high transmittance of over 90% in a wavelength between 300 and 800 nm. Thus, the epoxy-hybrimer coating film can be utilized as the passivation layer in the thin-film transistor.

Cyclo-aliphatic epoxy and methacrylate hybrimers were fabricated via the photocationic polymerization of cycloaliphatic epoxy oligosiloxanes and photoradical polymerization of methacrylate oligosiloxanes, respectively. The thermomechanical/thermal properties of these two hybrimers using different photo-polymerization mechanisms were compared. Although both oligosiloxanes showed similar degrees of condensation, siloxane network structures, and sizes, the cycloaliphatic epoxy hybrimer showed improved thermomechanical/thermal properties as compared to the methacrylate hybrimer. This was attributable to a highly crosslinked network structure developing from the living characteristics of photocationic polymerization and the short, compact organic chains of the cycloaliphatic epoxy hybrimer as compared to the methacrylate hybrimer.