Research On Photoelectric Sensing Device Based On Zero-Dimensional CsPbBr₃ Nanocrystal And Two-Dimensional MoS₂ Heterojunction

In recent years,the development of low-dimensional materials in photoelectric sensing devices is in full swing.In the application of photodetector,zero-dimensional colloidal nanocrystals photodetector and two-dimensional graphene and transition metal dihalide photodetector have made remarkable progress.The zero-dimensional and two-dimensional heterojunction photodetector,which combines the high extinction coefficient of zero-dimensional colloidal nanocrystals and the high mobility of two-dimensional materials,has greatly promoted the performance of the photodetector.However,the quantum trapping effect of colloidal nanocrystals will lead to faster recombination of radiation and non-radiation,which limits the dissociation of excitons and further affects the performance of photodetectors.In this paper,aiming at the existing difficulties of the above-mentioned zero-dimensional and two-dimensional heterojunction photodetector,a new phototransistor structure is proposed and its photoelectric performance is systematically explored,and compared with the traditional pure two-dimensional material photodetector and zero-dimensional and two-dimensional heterojunction photodetector in detail,and its application in the field of optical synapse is further explored.The main contents are as follows:1.Combining Tetracene with zero-dimensional nanocrystals,a novel and efficient exciton dissociation system is constructed for the first time.Under this system,the ultra-fast hole transfer rate can reach about 7 ps and the long-life charge separation state can be achieved.The power-dependent experiments show that the system can extract more than five excitons from a single nanocrystals,which provides a basis for the design of high-performance photoelectric sensing devices in the future.2.A phototransistor based on（Tetracene:CsPbBr₃）-MoS₂ hybrid planar heterojunction structure is proposed,and its working mechanism and photoelectric detection performance are explored.The high extinction coefficient of CsPbBr₃nanocrystals is mainly used to realize high-efficiency light absorption,and the ultra-fast hole transfer rate and long-life charge separation state are realized by constructing a（Tetracene:CsPbBr₃）Type-Ⅱheterojunction,and the high carrier mobility of two-dimensional material MoS₂ is used to realize efficient extraction of photo-generated charges,so as to finally realize high-performance photoelectric detection.When the incident wavelength is 405 nm,the incident optical power density is 84.67 m W/cm²,and the source-drain bias voltage is 1 V,the photocurrent can reach 134.73μA;When the incident light power is 7.67 m W/cm²,the optical responsivity,external quantum efficiency and specific detection rate of the device reach 8.04 A/W,2,461.67%and1.66×108 Jones,respectively.The performance of（Tetracene:CsPbBr₃）-MoS₂ structure phototransistor is compared with that of traditional MoS₂ photodetector and traditional CsPbBr₃-MoS₂ photodetector.3.Based on the characteristics of（Tetracene:CsPbBr₃）-MoS₂ structure phototransistor,this paper further studies its application in the field of photoelectric synapses,which can simulate the synaptic behavior of biological vision,such as excitatory postsynaptic current,long-term plasticity and short-term plasticity of synapses,and can adjust the synaptic weight by changing the illumination time,illumination intensity and the number of light pulses.Aiming at the advanced learning behavior of biology,we successfully simulated the famous Pavlov dog experiment by using the synergistic effect of light and electricity,showing the excellent potential of the device in the field of photoelectric sensing.