Exciton Migration and Photo-Induced Degradation of MEH-PPV Organic Semiconductor in Solutions and Thin Films
Abstract: The study of MEH-PPV, Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], has been of great interest for its semiconducting properties, leading to the practical applications of creating organic light emitting diodes (OLED) and solar cell devices. This research is focused on the study of the mechanisms responsible for the photoluminescent (PL) degradation of MEH-PPV in both solutions and thin films. The PL spectrum of samples was collected using time-resolved optical spectroscopy along with the absorbance spectrum using UV-Vis spectroscopy as samples were degraded by 447 nm laser beam excitation. A blue shift was observed in the PL and absorbance spectra of MEH-PPV. The blue shift is more apparent from the thin film samples than those in solution. This blue shift in spectra is attributed to the degradation of low level exciton energy states causing the photo-generated excitons to reach higher energy states before radiative recombination.
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