Molecular oxygen and moisture as traps in poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene]:: locations and detrapping by chain relaxation

We investigate locations of molecular oxygen and moisture (O-2/H2O) serving as traps in poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) by measurements of field-induced thermally stimulated current, photoexcitation thermally stimulated current (PE-TSC), and dynamic mechanical analysis. Two broad peaks of PE-TSC are found at 212 and 325 K in the samples with O-2/H2O-rich MEH-PPV, which are in reasonable agreement with those of the side chain and main chain relaxation, respectively. These traps can be attributed to the presence of O-2/H2O (most likely molecular oxygen) in the side chain region and the amorphous main chain region, and the detrapping process is induced by chain motions under elevated temperatures. (C) 2003 American Institute of Physics.