Photodetecting and electronic properties of poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)-ethyl viologen dibromide blended thin film diodes

Photodetectors operating in the visible spectrum have been realized using composites of the semiconducting polymer poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and the organic material ethyl viologen dibromide (EVD). Active polymer-organic thin film thicknesses were ∼ 70 nm. The external quantum efficiency of the MEH-PPV/EVD blend photodiodes was found to be twice that of pure MEH-PPV devices. The increase in photoconductivity of blended MEH-PPV/EVD photodiodes may be due to ultra fast charge transfer by EVD dication. The breakdown voltage was dependent on the EVD concentration and ranged between - 12 and - 20 V. Hysteresis behavior was observed in studied devices and could be due to a charge trapping