Low-Voltage High-Performance Organic Field-Effect Transistor And Driving OLED Display

Recently,organic field-effect transistors（OFETs）have attracted worldwide attention,owing to their attractive features of minimizing the processing cost,superior intrinsic mechanical flexibility,and sustainable performance improvement.OFETs-driven organic light-emitting diode（OLED）displays are considered to be one of the most promising new technologies,which can meet the dual requirements of device functionality and flexibility.However,the high operation voltage,poor stability,and low drive current density of OFETs are bottlenecks preventing further advances towards the targeted applications.Aimed at these challenges,this thesis devotes to solve the key issues,namely,reducing the operation voltage and improving the stability as well as the performance of OFETs.Section I:In this work,using PMMA/PAA as the gate insulating layer,which not only prepares high-quality polymer capacitors,but also improves the compatibility with organic semiconductor.At the same time,assisted assembly strategy based on a PAA with the unique nanostructure surface structure is developed to effectively grow C8-BTBT ultrathin singe crystal arrays using a facile drop-casting method,decreasing the semiconductor/dielectric interface trap density.Owing to the enhanced charge transport efficiency benefited from high crystallinity and ultrathin structure,the OFETs demonstrate the highest mobility of 18.63 cm²V^-1s^-1,while maintaining a low operating voltage of-3 V.The results shed light on the large area fabrication of organic single crystals on polymer dielectrics toward high-performance and integrated plastic electronics.Setion II:Overcoming the trade-offs among power consumption,high-mobility,and device stability has been a long-standing issue for wearable electronics.We report a van der Waals integration strategy to fabricate OFETs that helps to reduce subgap density and improve the device performance.The OFETs are successfully fabricated with a PS as the gate dielectric layer,two-dimensional molecular crystals of DNTT as the channel active layer in a non-destructive way.Attractively,the device can significantly reduce subgap density with only 2.7×10¹⁰ cm^-2 e V^-1,resulting in a small SS of 76.7 mV decade^-1 and a low operation voltage down to-3 V.The fabricated devices exhibit excellent p-channel characteristics with a maximum mobility of 16.32cm²V^-1s^-1,and current on-off ratio of ～10⁸ while operating at-3 V.The devices exhibit a remarkable stability under effects of gate bias stress and large number of repeated transfer scans with negligible performance spread.In addition,these devices remain highly stable without any degradation even after 500 days.That’s all indicated this method is an effective strategy to fabricate low-voltage,high-performance,and high-stability transistors.Section III:For the AMOLED pixel circuit,the TFT threshold voltage shifting,the low driving current density,and the high operation voltage influence the display performance.In order to solve the problem of the OFETs applied to flat panel display technology,the high operation,low driving current and operational stability.Here the PAA as the buffer layer on the Al₂O₃ surface make it compatible with organic semiconductors without degrading its insulating property.As well as liquid-liquid interface acted as a molecularly flat and defect free surface are used to grow high-quality and ultrathin two-dimensional organic crystals.Using a simple transfer method,the high-mobility active layers and bias-stable dielectric substrates are combined.OFETs based on the C10-DNTT two-dimensional single crystal as the active layer exhibit a remarkable mobility of 20.23 cm²V^-1s^-1,working voltage within-3 V,a high ON/OFF ratio（～10⁸）,and a high current density(2.2μA cm^-2).The device can fulfill the demand for low-voltage operation,high current density,bias stress stability at the same time,and a light emission of RGB OLED pixels are drivened by applying a V_Gonly-8 V.