Studies On Preparation And Sensing Properties Of Polymer Field-Effect Transistors

Polymer semiconductors with properties, such as variety in molecular design, light weight, mechanical flexibility, good compatibility with large-area and flexible a substrates/materials and solution-processability, endow them with potential for broad applications in various future advanced electronics, such as electronic skin, tongue, nose, and phototransistor, etc.This work investigated the fabrication, electronic characteristics, and sensing properties of PBIBDF-BT, a conjugated polymer containing BIBDF units, effect-filed transistors.(1) An oxygen sensing transistor based on the PBIBDF-BT conjugated polymer is investigated. The devices cast form cold PBIBDF-BT solution exhibited electron-mobility up to 1.80 cm2V-1s-1. Moreover, the device exhibited both hole-and electron-carriers transport sensing with different oxygen atmospheres, and the mobility, threshold voltage, on/off current ratios, and subthreshold swing are change with the change between absorbing and desorbing oxygen into semiconductor layers. This work further analyzed the under laying reason for how oxygen can influence the field-effect characterizations. In addition, the behavior of drain current dependent on oxygen have been molded with different oxygen atmosphere indicating the donor-acceptor conjugated polymer based transistor might be an oxygen sensor in practical application.(2) A facile and controllable phase-separation route toward fabrication of microporous PBIBDF-BT semiconductor film is proposed. We blending the polymer semiconductor with low Mw polymer called PBA, and in the process of spin-coating PBIBDF-BT/PBA blends, a phase-separation behavior between PBIBDF-BT and PBA, and after removed the PBA components on PBIBDF-BT/PBA films with acetone, the microporous PBIBDF-BT films were obtained after the steps. The PBIBDF-BT microporous film based sensor exhibited pronounced selectivity to ammonia gas, and showed higher sensitivity of 847 at an NH3 concentration of 10 ppm, and lower response time/recovery time of several second or even blew 1 second. Moreover, the sensor showed both a hole- and electron- carrier transport response to ammonia when exposure device NH3 with different concentrations, and the ambipolar response to NH3, which possess the two parameters, such as mobility and threshold voltage (VTH) for P-type and N-type response, would be increased greatly the accuracy of detecting NH3 with different concentrations.(3) A photoresponsive polymer thin-film transistor based on a donor-acceptor conjugated polymer ambipolar semiconductor (PBIBDF-BT) is proposed in this work. The device exhibited both hole- and electron-carrier transport response to incident light with photoswitching speeds below 14 ms. In addition, the photocurrent-/dark-current ratio and the photoresponsivity were 4552 and 108.43 mA W"1 for the p-type channel, and 1044 and 38.72 mAW"1 for the n-type channel, respectively. The PBIBDF-BT films exhibit more pronounced sensitivity to red light than previous polymer semiconductors, and the drain current gradually increased with an increase in the illumination intensity. The influence of mobility of PBIBDF-BT thin films, which were formed via spin coating at different spinning speeds on the OTS/SiO2/Si substrate, on the phototransistor response to light illumination was further investigated.