Semiconducting polymer diodes: Large size, low cost photodetectors with excellent visible-ultraviolet sensitivity

Photodiodes fabricated from conjugated polymers exhibit excellent sensitivity to visible-UV radiation. The photosensitivity increases with reverse bias voltage. The photoresponse of diodes fabricated from poly(3-octyl thiophene) is relatively flat in the visible and near UV; for wavelengths shorter than 550 nm, the absolute sensitivity is greater than 0.3 A/W under reverse bias of 15 V, larger than that of commercial UV-enhanced Si photodiodes. Photodiodes made from poly2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene, MEH-PPV, sensitized with C60, show similar sensitivity. The ease of fabrication into large size, arbitrary shapes, and even onto flexible substrates makes the polymer photodiode a novel photodetector with potential for use in a wide range of applications.