A Van Der Waals Photo-Ferroelectric Synapse

For hardware artificial intelligence, the central task is to design and develop artificial synapses with needed characteristics. Here, the design and experimental demonstration of a van der Waals (vdW) photo-ferroelectric synapse are reported. In the photo-ferroelectric synapse, the synaptic memory is extracted by reading the photocurrent, and written or edited by electrical pulses. The semiconducting vdW organic-inorganic halide perovskite ((R)-(-)-1-cyclohexylethylammonium)PbI3 (R-CYHEAPbI(3)) photo-ferroelectric serves as the model photo-ferroelectric channel. Here, the vdW organic layer provides ferroelectric dipole and the PbI6 octahedron is responsible for photon absorption and charge transport. The R-CYHEAPbI(3) photo-ferroelectric synapse show a writing/reading dynamics with >200 synaptic states, close to 10(3) on/off ratio, and reasonable endurance and retention characteristics. With the experimentally measured weight dynamics (parallel reading through ferroelectric photovoltaic effect and writing by electrical pulses) of R-CYHEAPbI(3) synapses, the feasibility of using a crossbar circuit to implement classic training and inference of hand-written digits is presented. An image recognition accuracy of up to 90% is obtained. The demonstration of such a vdW photo-ferroelectric synapse opens a window in the design of advanced devices for artificial intelligence.