Pentacene-Based Photodetector in Visible Region With Vertical Field-Effect Transistor Configuration

Abstract

Electrical and detection performances of pentacene-based photodetector with vertical field-effect transistor (VFET) configuration were investigated in full visible region. By comparing with planar FET-based photodetector ITO/ PMMA(520 nm)/Pentacene(35 nm)/Au, the VFET-based photodetector ITO/Pentacene(80 nm)/Al(15 nm)/Pentacene(80 nm)/ Au exhibits better performance. At an output current of ca. -8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> A, the threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) was -0.61 V for the VFET-based device at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = -2 V, but V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> = -7.1 V for the planar one at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = -12 V. The performance of photodetectors depends on incident monochromatic light, and the VFET-based photodetector showed a maximum responsivity of 188 mA/W and a photosensitivity peak of 588 under 350-nm light, which were ~11.75 and 2.83 times as that of the planar one, respectively. Therefore, it provides an easy way to get the VFET-based organic photodetectors in full visible region with excellent photosensitivity, responsivity, and light selectivity, showing its promising application in all-organic image sensors working at low voltages.