Enhancement of light emission in molecular thin films

Towards possible fabrication of organic solid-state lasing, enhancement of light-emission in molecular thin films was considered in terms of polarizat ion control by epitaxial orientation of linear x-conjugating molecules, int roduction of low-dimensional confinement structures and planar waveguiding in dye-doped sol-gel films. Epitaxially grown needle crystals of vapor-depo sited p-phenylene oligomers on a KCl substrate exhibited a polarized blue l ight-emission, which was self-waveguided along the needle axis, due to the uniaxial molecular alignment. Dotlike and disklike structures of vapor-depo sited p-phenylene molecules were expected to be an effective in-plane emitt er due to standing orientation of their transition dipoles. Sol-gel glassy films of SiO2/TiO2 doped with fluorescent dyes demonstrated optically pumpe d lasing based on the asymmetric planar weveguide under multiple inward ref lection conditions by controlling their refractive indices of the matrix fi lms.