Efficient full-color electroluminescence and stimulated emission with polyphenylenes

We demonstrate the fabrication and characterization of highly efficient red-green-blue (RGB) and white light emitting devices based on poly(phenylene) type materials as the hexaphenyl and the methyl substituted laddertype poly(para phenylene) (m-LPPP). The RGB-devices are fabricated with an external color conversion technique based on PHP, whereas the white light emission is generated by an internal excitation energy transfer from the blue m-LPPP component to a red light-emitting polymer in a polymer blend, which is used as the active layer in a light-emitting diode. We present photophysical properties, like spectral line-shape site selectivity of photoluminescence (PL), and electroluminescence of bulk poly(para-phenylenevinylene) PPV films and isolated PPV chains incorporated into a self- assembled matrix material, which leads to the formation of a regular hexagonal array of channels with a diameter of about 15 angstrom, in which the conjugated polymer chains are contained. The structure of the nano-composite in organic- light-emitting-diodes. A suitably structured m-LPPP waveguide shows a spectrally very narrow high directional blue-green light output when optically pumped. The high optical gain of m-LPPP is a results of the spectral separation of stimulated emission and photoinduced absorption bands, thus spectral narrowing is even observable in below cut-off waveguides. Under resonant excitation conditions, we observe strong stimulated Raman scattering.