A monolithically integrated organic photodetector and thin film transistor

We demonstrate a vacuum deposited molecular organic photodetector (OPD) integrated with a top gate, bottom-contact. pentacene-based organic thin film transistor (OTFT) for use as a switchable organic passive pixel sensor in focal plane imaging arrays. The hetero-junction OPD consists of a 110 angstrom thick film of the donor, boron subphthalocyanine chloride, and a 325 angstrom thick film of the acceptor, C-60. The OTFT switch allows the photodetector to be switched between an active (ON) state with a light intensity dependent photocurrent peaking at 20 nA, and an inactive (OFF) state with current < 50 pA, corresponding to an 8-bit dynamic range. The integrated device has a spectral coverage from wavelengths of 400-600 nm, and a pixel switching frequency > 400 kHz. The integrated structure is fabricated at room temperature, making this circuit compatible with low cost, flexible plastic Substrates. (c) 2009 Elsevier B.V. All rights reserved.