Research Of Multi-functional Organic Thin-film Transistors

Multi-functional organic thin-film transistor?OTFT?combines the switching capability of OTFT and other functions?e.g.memory,light-emitting?in a single device,which has been a hotspot in the field of research of organic/inorganic semiconductors and functional devices.The development of multi-functional OTFTs follows a trend of miniaturization and portability.Therefore,in this article,we established novel multi-functional transistors by coupling triboelectric nanogenerators?TENGs?,which were controlled by the contact-induced electrostatic potential of TENGs rather than traditional gate voltages.Furthermore,based on iridium ionic complexes,we proposed novel kinds of transitors giving emission from gate dielectric layers.Our research includes three parts as follows:1.We proposed an organic triboelectric transistor?OTT?based on Ta₂O₅,in which the channel current(I_DS)was modulated by mechanical force instead of traditional gate voltage.Wesuccessfully fabricated high-performance OTT by controlling the film morphology and optimizing different functional layers.The device showed excellent transistor characteristics and stability.The average threshold voltage?V_T?was below 1 Vand the on/off current ratio was over 10⁵,while the performance remained same after one year.Furthermore,the OTT could be used to control light emission of an organiclight-emittingdiode?OLED?.2.We proposed an organic triboelectric transistor memory?OTTM?based on Ta floating gates,in which externally applied touch signals could be memoried.Using Ta floating gate to enhance the trap density and polymethyl methacrylate?PMMA?to improve mechanical stability,we successfully fabricated a high-performance flexible device with a large memory window?16.3±0.4 V?,a high ON/OFF ratio?10⁵?and a long retention time?10⁵s?.The device remained stable after 1,000 iterations of compressive or tensile bending tests,and could still work after 2 months.Then,we discussed the working mechanism of OTTM.Moreover,by coupling with an OLED,we established an all-flexible wearable touch monitoring system for real applications.3.Based on [Ir?dmfpz?₂?dtb-bpy?]PF₆andzinc tin oxide?ZTO?,we designed and fabricated a novel simple-structured light-emitting transistor which gave area-emission from dielectric layer under a low voltage.Owing to the forming of electrochemical double layers,we successfully decreased the threshold voltage?V_T?of the device to 0.85 V,and the charge carrier mobility of the device was over 48.3 cm² V^-1s^-1.The light emission could be controlled through V_GS and V_DS.To prove the wide applicability of our approach,we fabricated similar device based on another iridium ionic complex,[Ir?ppy?₂pyim]PF₆.We carried on systematical research by mixing this complex with different mass concentration ratios of PMMA.Furthermore,we demonstrated the different working mechanisms of the devices with or without PMMA.Our research laided the foundation of the realization of multi-functional organic triboelectric transistor in the future.