Reasonable Design,accurate Synthesis,and Application Exploration Of New Information Storage Materials

Non-volatile transistor memory devices(NVTM)have attracted great attention due to their unique advantages such as non-destructive reading,good compatibility with integrated circuits,solution-processability as well as mechanical flexibility.Efforts have been devoted to improving the data retention,endurance,on/off ratios,non-destructive readout capability,mechanical flexibility,printing feasibility,as well as reducing operating voltages and programing pulse width;in particular,the major attention has been put on increasing the data storage density.Though tremendous progresses have been made,it is still a great challenge to achieve NVTM with high data storage density based on solution-processable dielectrics and semiconductors which could eventually adapt to high-throughput manufacture.Additionally,data security is a rising concern,and becomes increasingly important,particularly in military and financial field.Nevertheless,data encryption and protection based on NVTMs has been rarely investigated.This thesis have done the following works to address above problems.(1)Nonvolatile transistor memories(NVTMs)are fabricated based on a polymer blend dielectric containing poly(pentafluorophenyl acrylate)(p PFPA)and branched-poly-(ethylene imine)(b PEI).Detailed studies reveal this dielectric not only exhibits a high dielectric constant(k=285 at 20 Hz),apparent polarization hysteresis,and robust mechanical properties but also endows a transistor(PBTTT-C14 as semiconductor)with ultrahigh mobilities(7.5 cm~2 V^-1 s^-1)and on/off ratios(10~7).By virtue of this,NVTMs possessing an eight-level storage capability at low operating gate voltages are demonstrated,with good data retention and endurance of over 10~5 s and 100 cycles,respectively.More importantly,the drain current can also be well controlled by the gate voltage pulse width,leading to NVTMs with two-dimensional(voltage and time)storage capability.Further,the application of the NVTMs to data recording,encryption,and protection is demonstrated,with a desirable security feature,opening the door to NVTMs with higher performance.(2)Nonvolatile OFET memory devices using different p PFPA/b PEI cross-linked polymers as the dielectric layer are fabricated.The influence of b PEI content on the electrical property and memory performance of devices are systematically investigated.The results demonstrate that the introduction of b PEI into p PFPA can significantly enhance the capacitance and dielectric constant of the p PFPA/b PEI cross-linked polymer dielectrics,but it also causes a slight increase in the leakage current density.Besides,the excess b PEI induces more morphology defects of the semiconductor film,leading to an apparent decrement in charge mobility.Transistors with the 119:250 p PFPA/b PEI dielectric layer exhibit the highest on/off current ratio(?10~7 at V_g=-20 V)and a relatively low hole mobility of 0.38 cm~2 V^-1 s^-1.Moreover,the corresponding memory devices show good reliability in information record with a data retention time over 10~5 s,indicating that an appropriate amount of b PEI is crucial for improving the stability of the memory devices.