New orange-red light emitting diode from poly[2-(5-cyclo-hexylmethoxypentyloxy)-5-methoxy-1,4-phenylenevinylene]

Poly[2-(5-cyclohexylmethoxypentyloxy)-5-methoxy-1,4-phenylenevinylene] (PMCYHPV) was synthesized through dehydrohalogenation polymerization. This polymer shows good solubility in common organic solvents. The absorption and photoluminescence (PL) emission maxima of PMCYHPV are 497 nm and 590 nm, respectively. The electroluminescence (EL) properties of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and PMCYHPV were studied by means of the EL spectra, current-voltage characteristics, and EL power-current characteristics. The measured relative EL quantum efficiency of PMCYHPV is about 6 times higher than that of MEH-PPV. The EL enhancement of PMCYHPV originates from the reduction of non-radiative decay of excitons caused by better separation of the polymer chains due to the rigid cyclohexyl side group. Furthermore, we found that the PL quantum efficiency of PMCYHPV is 15% higher than that of MEH-PPV.