Temperature effects on photoluminescence of poly [2-methoxy-5-(20-ethyl-hexyloxy)-1,4-phenylene vinylene]

We present photoluminescence studies as a function of temperature from poly [2-methoxy-5-(20-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). The photoluminescence transition energies are red-shifted with decreasing temperatures that can be explained by the suppression of the torsional motion in the polymer backbone, which increased the effective conjugation length of the polymer. The enhancement of the relative intensity of the 0–1 to 0–0 vibronic band can be attributed to the formation of aggregates in coincidence with the vibronic 0–1 bands.