Voltage-Dependent Luminescence Properties of Molecularly Doped Polymer System

Single-layer light-emitting diodes (LEDs) are fabricated using a mixture of a blue-emitting polymer and green-emitting 9, 10-bis (phenylethynyl)anthracene as emitting layer. The blend device with these two components in the emitting layer exhibits voltageinduced evolution of the electroluminescence. But when polystyrene is also blended into the emitting layer, the EL spectra show emission bands from both ether–PPV and BPEA in proportion to concentrations of the two materials, and the spectra exhibit no change with applied voltage. This implies that doping inert polymer is helpful in suppressing voltage-induced evolution of electroluminescence in LED blends.