Photosensitive Organic Field-effect Transistors Based On Rare Earth Phthalocyanine:from Material Synthesis To Device Preparation

The application of organic semiconductor materials and devices is a hot research topic in the field of organic electronics and the gratifying results have been achieved. Due to its low power consumption, light weight and can be produced in large area, Organic Field-effect transistors (OFET) have wide application prospect. As one of the important branches of OFET, Photosensitive field-effect transistor (PhotOFET), which with high sensitivity and low noise factor, have become a new type of light detector and have widely attention and study. This paper has carried out the following work around two aspects, such as the preparation of rare earth phthalocyanine photosensitive materials and its application in PhotOFET device.1. The rare earth phthalocyanine photosensitive organic semiconductor materials, Phthalocyanine neodymium (NdPc2) and phthalocyanine erbium (ErPc2), were synthesized. The tests of ultraviolet-visible absorption of thin film show that NdPc2and ErPc2have strong absorption on red light and the maximum value of light absorption coefficient were1.4×105cm-1and1.1×105cm-1respectively. Therefore, as the ideal red light photosensitive materials, NdPc2and ErPc2can be used in organic red light detector.2. Two kinds of organic semiconductor materials synthesized above were used in the preparation of NdPc2and ErPc2single-layer photOFET respectively based on the Si/SiO2substrate. Among them, the maximum value of light/dark current ratio of the NdPc2single-layer PhotOFET is104and the photoresponsivity is7.04A/W which with the incident light intensity of0.004mW/cm2when gate voltage is-50V and drain voltage is-100V.3. In order to improve the photosensitive properties of photOFET based on phthalocyanine neodymium, we further introduce the high mobility of n type organic semiconductor material, C60, as channel transport layer and prepare the C60/NdPc2heterojunction PhotOFET. The maximum value of light/dark current ratio of device can be up to105. Also, the photoresponsivity of device is214.8A/W with the same incident light intensity when gate voltage is50V and drain voltage is100V. Thus, collocation of C60with high mobility materials makes C60/NdPc2heterojunction PhotOFET has better photosensitive properties.4. The CuPc/ErPc2plane-heteroj unction device based on ErPc2as photosensitive layer was also prepared in experiments. With the incident light intensity of5mw/cm2, the maximum of light/dark current ratio of device valued102can be achieved. When gate voltage is50V and drain voltage is100V, the maximum photoresponsivity of device can be obtained by0.16A/W.