The effect of aging process on the parameters of a thin film optoelectronic NAND logical gate

An optoelectronic logical gate NAND composed of thin film photoconductive (PC) and electroluminescent (EL) elements. In the system was supplied with sinusoidal voltage with equal values of amplitude and frequency. The input signals were two rectangular light pulses, illuminating the respective photoconductive elements, and the output signal was the luminance of the electro-luminescent cell. The process of natural aging, which caused changes in parameters of PC elements, influenced also the changes in characteristics of the system composed of these elements. For EL element subjected to aging in normal conditions without applied voltage, the luminance of the light was lower by about 20% than for element immediately after their preparation. A variation of the parameters of PC and EL elements by the aging process caused then a decrease of the signal on the output of NAND gate and also an increase in the lag of the output signal in relation to the input signal.