The Study Of Organic Thin Film Transistors Gas Sensors Based On Thiophene

Organic Thin Film Transistor（OTFT）gas sensors have distinctive advantages,such as multi-parameter detection, so it attracted wide attention of sensors researchers at home and abroad. The dissertation discussed electrical properties and sensitive responses of OTFT gas sensors to various gases. The devices based on n+ Si substrate with 195 nm SiO₂ insulating layer. Different sensitive mechanisms were put forward for OTFT gas sensors based on different active layers. In addition, A 3×2 OTFT gas sensor array was designed and fabricated in this dissertation.Firstly, three OTFT gas sensors based on α-6T thin film, α-6T/C₆₁ heterojunction composite thin film and organic/inorganic composite thin film（α-6T/ZnO） were prepared respectively. The electrical properties and sensitive responses to NH₃ of these devices were measured. Results showed that the response of the device doped C₆₁ increased 5.04 times than that of α-6T devices. Their sensitive mechanisms were analyzed in detail. Results also showed that the device of 3:1α-6T/ZnO-TFT enhanced saturation of output curve, the recovery and baseline drift phenomenon were all improved.Then six OTFT devices owning different active layer structures such as P3HT-TFT, P3HT-C₆₁-TFT, C₆₁-P3HT-TFT, P3HT/C₆₁-TFT, P3HT-RGO-TFT and P3HT/Tipspentacene-TFT were fabricated. Their electrical properties and gas sensitive responses to NH₃ or NO₂ were measured respectively. Among all those devices, P3HT/C₆₁-TFT exhibited the most optimal properties. The sensitive mechanisms were presented in the dissertation by combing heterojunction structure with SEM morphology. In addition, compared with P3HT-TFT, the value of IDS and sensitivity of P3HT-RGO-TFT increased almost one order of magnitude, and its response and recovery were also improved. P3HTRGO-TFT also improved the phenomenon of baseline drift. In addition, we think that the two-dimensional（2D） lamellar structure of RGO played a key role in P3HT-RGO bilayer film. The effects of film thickness and temperature on the sensitive properties of the P3HT/Tips-pentacene OTFT were also studied in the dissertation. It was found that the sensitivity of the device to NO₂ under 60℃ circumstance was 1.6 times higher than that at room temperature. While, the device with 1ml gas injection amount improved the responses to NH₃ than that of 0.5 ml.Finally, a 3×2 organic thin film transistor array owning five different channel width and length was designed and prepared. Simultaneously, the whole process and parameters of preparation were introduced in detail.