Organic Optoelectronic\nSynaptic Transistor with Enhanced\nUV Light Response Based on Insulating Polymer-Assisted p–n\nHeterojunction

Optoelectronic synaptic transistors possess the capability\nto simultaneously\naccomplish perception and process functions within a single device,\nthereby not only addressing the limitations of von Neumann architectures\nbut also serving as a promising candidate for emulating neural vision\nsystems. The extensive range of organic semiconductor materials offers\na plethora of possibilities for device fabrication; however, the severe\nrecombination of photogenerated carriers imposes limitations on the\nutilization of organic p–n bulk heterostructures in synaptic\ntransistor construction. By incorporating an insulating polymer and\nimplementing a p–n planar heterojunction architecture, the\n30% PCBM@PAN-DPPDTT transistor was constructed using the PCBM/DPPDTT\nheterojunction and the PCBM@PAN photoresponsive charge trapping layer.\nDue to the effect of the photoresponsive charge trapping layer and\ninterface traps, the device not only overcomes the shortcomings of\np–n bulk heterojunction and exhibits typical synaptic properties\nbut also demonstrates a significantly enhanced response to ultraviolet\n(UV) light, exhibiting nearly four times more excitatory postsynaptic\ncurrent (ΔEPSC) compared to the device lacking PCBM. The transistor\nmatrix was employed to simulate the image perception and memory functions\nof the human neural vision system. Furthermore, an artificial neural\nnetwork with high recognition accuracy (∼95%) of handwritten\nnumbers was constructed. This study proposes an additional approach\nfor mitigating the issue of rapid recombination of photogenerated\ncharge carriers in the construction of optoelectronic synaptic transistors\nby utilizing p–n heterojunction.