Interfacial Trap Effect Modulation of Organic Phototransistors for Artificial Vision System

Artificial photoelectric synaptic devices are promising candidates for simulating the perception, processing, and memory functions of biological visual information. Dielectric layer interface modification is a simple and effective strategy for the fabrication of light stimulated synaptic devices. In this work, the dielectric layer interface was tuned by varying the terminating groups of self-assembled monolayers (SAMs), whereas the polymer polydiketopyrrolopyrrole-selenophene with hybridized siloxane side chains (PTDPPSe-4Si) was used as the active layer for fabrication of the transistor devices. Enhanced optoelectronic performance was observed in the fabricated devices that were treated by pentafluorophenylpropyltrichlorosilane (FPPTS) due to the presence of more interfacial charge traps. The photosensitivity and detection rate were found to be up to 105 and 1011 Jones, respectively. Furthermore, it was also shown experimentally that the interfacial charge trapping effect was caused by a combined effect of electron trapping by the SAMs-modified interface and traps present within the active layer. Biological synaptic plasticity was successfully simulated using FPPTS/PTDPPSe-4Si-based devices. The memory and forgetting processes of biomimetic visual information were also simulated. Finally, conventional neural networks were used for image recognition, achieving a recognition rate of over 95%.