Optical neural device based on memory-type organic photoconductors

A variable-sensitivity organic-photoconductive device has been developed by using a memory-type organic photoconductor. The device is composed of an input layer and a memory layer acting as a charge generation and a charge transport layer, respectively. A persistent high-sensitivity state, which corresponds to a modulation of synaptic weights in a neuron model, was obtained by blue light illumination. A photochemical reaction of thiomichlerʹs ketone (TMK) in the memory layer was found to be responsible for the memory formation. As a potential application of this memory-type organic photoconductor to an optical neural device, 2-D pattern storage and calculations were performed successfully.