MEMORY EFFECT OF AN ORGANIC PHOTOCONDUCTOR AND ITS APPLICATION TO A NEURON MODEL

A new type of organic photoconductor composed of 9-ethylcarbazole-3-carbaldehyde diphenylhydrazone (DPH) dispersed in a polycarbonate polymer (PCR) film, when in the presence of thio-Michler's ketone (TMK), was found to exhibit a sustained state of enhanced conductivity following visible irradiation. At room temperature, the enhanced current is observed to decay slowly over a period of a day and when heated it rapidly returns to its original state. A potential application of this ''memory'' effect to an artificial neuron model, using such memory-type organic photoconductors as optically controllable interconnections, is discussed. A liquid-crystal cell is used to demonstrate a nonlinear-saturated response dependent on a weighted input electric signal.