Fabrication of p-pentacene/n-Si organic photodiodes and characterization of their photoelectric properties

We have fabricated p-pentacene/n-Si organic photodiodes by thermal evaporation of pentacene films at 25 (RT), 60, and 80 degreesC. Our pentacene films exhibit the main absorption peak (highest occupied molecular orbital-lowest unoccupied molecular orbital gap transition) at 1.82 eV and photoelectric effects were clearly observed from our p-pentacene/n-Si diodes when illuminated by a monochromatic red light of 1.85 eV (670 nm). Excellent photoresponsivity of 2.6 A/W and the photoresponse time of less than 40 ns have been demonstrated. The photodiodes exhibited typical rectifying behavior in the dark and the leakage current increases with the deposition temperature. (C) 2003 American Institute of Physics.