Self-Powered Optoelectronic Device with Depression-Related Synaptic Functions

Great effort has been made for the development of optoelectronic synapses that play an important role in constructing artificial visual systems. However, most reported optoelectronic synaptic devices have difficulty mimicking depression-related synaptic functions under optical stimulation. Herein, we report a self-powered optoelectronic synaptic device based on an organic heterojunction of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/copper phthalocyanine (CuPc)/hexadecafluorophthalocyanine copper (F₁₆CuPc). A dielectric layer of P(VDF-TrFE) was induced to generate an energy barrier to improve its synaptic performance. The fabricated device exhibited inhibitory postsynaptic current (IPSC) function under continuous stimulation of 660 nm optical pulses. Some basic functions of biological synapse, such as paired-pulse depression (PPD), spiking-number-dependent plasticity (SNDP), and spiking-rate-dependent plasticity (SRDP), were successfully mimicked. The capability of the device as a low-pass filter for image processing was also demonstrated.