New functional properties of organic-inorganic hybrid glasses and their application to photoelectronic devices

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The main results obtained through this research are itemized below : (1) Photocurrent in polysilane-titania hybrid thin films has been measured. It has been found that photocurrent in polysilane-titania hybrid thin films is increased by about 1000 times in comparison with that in polysilane-silica hybrid thin films because of photo-induced charge transfer at polysilane/titania interface. Such photoconductive properties make it possible to apply these hybrid thin films to photoelectric devices such as photosensors and solar cells. (2) Optical properties of hybrid thin films, poly(di-n-hexylsilane) (PDHS) dispersed in a zirconia matrix prepared by a sol-gel method, have been studied. It is found that thermochromism of PDHS is suppressed in the PDHS-zirconia hybrid thin films, and that the refractive index of the hybrid, n, is continuously decreased with increasing temperature, T. The thermo-optic (TO) coefficient of the hybrids, dn/dT, is found to be -4×10^<-4>℃^<-1> and such a high valu … More e of dn/dT enables us to apply the hybrids to optical devices such as TO switches and optical deflectors. (3) Thin films of polymethylphenylsilane (PMPS)-SiO_2 nanoparticles (np-SiO_2) whose surfaces are chemically modified by a phenyl group have been prepared from the tetrahydrofuran solution. The refractive index of the hybrid can be changed by increasing np-SiO_2 concentration from 1.68 to 1.47. The solution coating process of the hybrid enables us to fabricate important optical devices such as waveguides, filters and interleavers by printing (ink-jetting) methods. In addition, it is found that the effective conjugation length of PMPS is increased by three times in the hybrids, and that the hole drift mobility of the hybrid is increased by one order of magnitude in comparison with that of PMPS. (4) It has been established a preparation method for Au nanocrystal-dispersed PMPS hybrid thin films. The average diameter of Au nanocrystals in the hybrid is about 5 nm and the diameter of Au nanocrystals exhibits a very sharp distribution. Thus, the hybrid is suitable for the fabrication of single electron devices and nonlinear optical devices. (5) Hybrid thin films of polyfuorene (and its copolymers) and the np-SiO_2 show the improvement of photoluminescence quantum efficiency and hole drift mobility. It is shown that the hybridization is a promising method to improve device characteristics of photoreceptors, organic thin-film transistors and organic electroluminescent devices. Less