Study Of Organic Field Effect Transistors-based Deep Ultraviolet Photoelectric Memory And Artificial Synapses

Deep ultraviolet（DUV）photoelectric memory is widely used in military,civil and commercial fields such as military detection,environmental monitoring and medical analysis.Field-effect transistor-type photoelectric devices not only have good light responsivity,but also have signal amplification function,which have strong application potential in the field of DUV photoelectric memory.At present,the detection of DUV optical signals are mostly based on inorganic semiconductors with ultra-wide bandgap,but the disadvantages such as limited material selection,intrinsic rigidity and complex preparation process limit their practical application.Organic semiconductors have attracted wide attention due to their wide range of materials,solution treatment and low cost.However,most organic semiconductors have narrow bandgap,which makes their absorption efficiency for DUV light very low.In this paper,narrow bandgap organic semiconductors are successfully used as the active layer of organic field effect transistors（OFETs）to realize the detection and storage of DUV optical signal.Meanwhile,following the trend of rapid growth of information in the era of big data,the multilevel storage function of information in a single device is realized.Considering the relationship between the rapidly increasing amount of information and information processing while expanding the memory capacity,OFET-type DUV photon stimulated artificial synapse device with large capacity storage and fast processing function is prepared.The main contents of this paper are summarized as follows:（1）A novel nonvolatile solar-blind DUV photoelectric memory based on OFETs were fabricated by using organic semiconductor,which realized 16-level photoelectric memory states with erasable capability.The memory window reaches 23.8 V when the device is programmed for 10 s under the conditions of-40 V gate voltage and 254 nm DUV illumination(1.252 m W cm^-2).The memory retention time exceeds 10⁴ s,and the writing/reading/erasing/reading exceeds 100 times.The exposure dose of DUV can be determined by changing the exposure intensity and exposure time.The memory also shows high selectivity to 254 nm DUV light.In addition,DUV memory array for image storage has been successfully fabricated.This work provides a new approach to applying organic semiconductors to solar-blind DUV photodetectors.（2）An OFET-based artificial synaptic device for DUV optical signal stimulation was prepared.The excitatory postsynaptic current（EPSC）is as high as 21.00 n A under a single pulse with the light pulse intensity of 0.884 m W cm^-2 and the light pulse duration of 4 s.Paired pulse facilitation was also successfully simulated under two consecutive light pulse stimuli,achieving excellent short-term synaptic plasticity.With the increase of light intensity,time or frequency of light pulse,EPSC increases to a certain extent,and the relaxation time of current also lengthens.The artificial synaptic behavior changes from short term memory to long term memory,which successfully imitates the learning process of human brain.The OFET-based artificial synaptic device successfully achieves large capacity storage and fast processing of signals in the DUV domain.