Determination of aggregates as charge trapping and recombination centers in poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] by time-resolved electroluminescence spectroscopy

A presence of aggregates can give critical influences on photophysical properties of conjugated polymer. For poly[2-methoxy-5-(2(')-ethylhexyloxy)-1,4-phenylene vinylene], the authors found that the aggregates can serve as charge traps and recombination centers by using time-resolved electroluminescence spectroscopy, and that the emissions from isolated chains and aggregates show different dynamics. The authors also found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of aggregates lie within the band gap of isolated chains. Thus, the aggregates act as shallow traps for both electron and hole so that a reexcitation to HOMO and LUMO of isolated chains is possible. (c) 2006 American Institute of Physics.