Efficient full-color electroluminescence and stimulated emission with polyphenylenes

摘要

Abstract: We demonstrate the fabrication and characterization ofhighly efficient red-green-blue (RGB) and white lightemitting devices based on poly(phenylene) typematerials as the hexaphenyl and the methyl substitutedladdertype poly(para phenylene) (m-LPPP). TheRGB-devices are fabricated with an external colorconversion technique based on PHP, whereas the whitelight emission is generated by an internal excitationenergy transfer from the blue m-LPPP component to a redlight-emitting polymer in a polymer blend, which isused as the active layer in a light-emitting diode. Wepresent photophysical properties, like spectralline-shape site selectivity of photoluminescence (PL),and electroluminescence of bulkpoly(para-phenylenevinylene) PPV films and isolated PPVchains incorporated into a self- assembled matrixmaterial, which leads to the formation of a regularhexagonal array of channels with a diameter of about 15angstrom, in which the conjugated polymer chains arecontained. The structure of the nano-composite inorganic- light-emitting-diodes. A suitably structuredm-LPPP waveguide shows a spectrally very narrow highdirectional blue-green light output when opticallypumped. The high optical gain of m-LPPP is a results ofthe spectral separation of stimulated emission andphotoinduced absorption bands, thus spectral narrowingis even observable in below cut-off waveguides. Underresonant excitation conditions, we observe strongstimulated Raman scattering. !61