Detection of microwaves using the organic semiconductor poly(p-phenylenevinylene)

We report a new procedure to convert the polymer precursor poly(xylylidene tetrahydrothiophenium chloride) (PTHT) into poly(p-phenylenevinylene) (PPV) using microwave irradiation. Spin-coated PTHT films were irradiated at room temperature under ambient conditions in a commercial microwave oven, with varying power from 20 W to 100 W. Complete conversion was reached within only 5 min of irradiation for powers above 50 W, yielding PPV films with absorption and photoluminescence spectra that are practically indistinguishable from the spectra of thermally converted PPV films, which require ca. 2 h of a high temperature (∼200 °C) thermal treatment. In addition to a much faster conversion procedure, the irradiation with microwaves led to a red shift in the absorption spectrum of a PTHT film, which varied linearly with the time of irradiation. These films can then be used as low-cost, easy-to-use detectors of microwaves.