Study On The Photoresponsive Organic Field-effect Transistors Based On CuPc

With the development of the organic field-effect transistors (OFETs), photoresponsive organic field-effect transistors (PhotOFETs) has also attracted much attention of researchers. Because of its higher amplification and signal/noise ratio compared to photodiode and organic bipolar phototransistor, PhotoOFETs has a very broad development prospect at graphic sensors, photoelectric detectors, etc.This thesis is based on the conventional structure of the bottom gate top contact OFET with CuPc as active layer, and discuss different thickness of CuPc layer and different source/drain electrode materials influence on device performance.We found that OFET based on CuPc with Au as source/drain electrodes has typical FET characteristics. The device with a thickness of CuPc for50nm, can obtain an Ion/Ioff ratio about105, and when both the gate voltage and drain voltage is-50V, a drain-source current higher than-650nA can be gain. At the same time, we found the thickness of organic active layer has important influence on device performance, when the thickness of CuPc is50nm, device has best FET performance. However, the OFET use Au as electrode has a/Ipho/Idark ratio lower than1, and a Ion/Ioff ratio about103on illumination condition (wavelength655nm, intensity100mW/cm2), its photoresponsivity was about2.55mA/W.Then we studied the OFET use Al as drain and source electrodes, with different thickness of the CuPc layer. It is found that no FET characteristics could be observed with Al as the drain and source electrodes without illumination. But the device showed good photosensitivity and FET characteristics on illumination condition. When the thickness of CuPc is100nm, both the gate voltage and drain voltage is-50V, under a illumination of red laser (wavelength655nm, intensity100mW/cm2), a photocurrent up to100nA was obtained, the/Ion/Ioff and Ipho/Idark ratio was higher than104while the photoresponsivity was about0.83mA/W.