Effect of temperature on the spectral line-narrowing in MEH-PPV

The temperature dependence of the spectral line-narrowing (SLN) in poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) has been investigated. We compare the blue-shift with increasing temperature of the SLN, with that of the absorption and photoluminescence. We find that the effect of temperature on SLN is stronger in films spun from tetrahydrofuran than for films spun from chlorobenzene. The role of conformational disorder and the effect of film morphology is discussed. The temperature dependence of the photoluminescence is found to be greater than that of the absorption by an amount kT where T is the temperature of the sample.