Pentacene-based photodetector in visible region with vertical field-effect transistor configuration

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 photo-detector ITO/Pentacene(80 nm)/Al(15 nm)/Pentacene(80 nm)/ Au exhibits better performance. At an output current of ca. -8× 10^-7 A, the threshold voltage ( V _th ) was -0.61 V for the VFET-based device at V_DS = -2 V, but V_th = -7.1 V for the planar one at V_DS = -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.