FABRICATION OF ONE-DIMENSIONALLY ALIGNMENT-CONTROLLED ORGANIC NANO STRUCTURE AND CREATION OF ANISOTROPIC OPTO/ELECTRONIC DEVICES

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Organic thin films have high potential for next generation photoelectronic and photonic materials. Their physical properties heavily depend on the molecular orientation in the film. In this project, we aim to fabrication and characterization of low dimensional orientation-controlled organic thin films for electronic and photonic devices. Pentacene was vapor-deposited on a friction-transferred PTFE layer. The polarized absorption spectra of pentacene/PTFE double layer showed an anisotropic feature. Pentacene oriented uniaxially taking edge-on state on a PTFE layer. The electrical property of pentacene/PTFE double layer also indicated anisotropic feature. The field effect mobility along to the traverse of the friction direction was 4.2×10-1cm2/Vs. We succeeded in preparation of high performance organic FET films. Polarized polymer light-emitting diodes (PLEDs) have been constructed utilizing friction-transferred poly(9,9-dioctylhorene) (PFO) thin films. The friction transfer technique al … More lowed an oriented PFO to be deposited directly onto an indium tin oxide anode without an alignment layer such as polyimide. Polarized absorption and hotoluminescence spectra revealed that the polymer backbones are highly aligned in the friction direction. We fabricated PLEDs consisting of friction-transferred PFO as an emissive layer, vacuum-deposited bathocuproine as an electron transport and hole-blocking layer, and a vacuum-deposited LiF/A1 cathode. Highly polarized blue emission with an integrated polarization ratio of 31 and a luminance of up to 300 cd/m2 was observed from the PLEDs. Photo-induced molecular alignment behavior of azo dye derivative on a fused silica substrate prepared by spin-coating method was also investigated. When azo film was irradiated by linearly polarized UV light, the longitudinal direction of azo molecules aligned along the normal direction against to the polarization direction of irradiated UV light. The dichroic ratio of absorption intensity (I_⊥/I_<//>) of azo film after UV light irradiation was 6. Photo-induced alignment mechanism of azo molecule was explained by anisotropic diffusion model.Research results obtained in this project will be expected to contribute the creation of smart photoelectronic and electric devices with organic materials. Less