Photoresponsivity enhancement of pentacene organic phototransistors by introducing C60 buffer layer under source/drain electrodes

Pentacene organic phototransistors (OPTs) modified by introducing C60 electrodes buffer layer were fabricated. Compared with conventional single-layer pentacene OPTs, the devices with C60 buffer layer exhibited higher performance under illumination. Maximum photoresponsivity is 4.27 A/W at zero gate bias under 0.2 mW cm(-2), which is six times higher than that of single-layer device and exceeds that of most OPTs reported recently in the same conditions. The maximum photo/dark current ratio is also higher than 5 x 10(4). Meanwhile, the C60 modified device could obtain lower threshold voltage and higher field-effect mobility. These results suggest that single-layer OPTs modified by heterojunction buffer layer will obtain better optical response. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4756937]