Space Charge Limited Currents in Anthracene Crystals under Modulated Illumination

Space charge limited currents have been examined in anthracene crystals illuminated with a chopped beam of monochromatic light (λ = 420 nm). The beam was uniformly absorbed in the anthracene crystal. The primary objective of our research was to determine mechanisms responsible for the release and trapping of charge carriers in the case of space charge limited currents as a function of time. The experimental results concern the dependences of photocurrents on the frequency of light chopping, light intensity, voltage and current decay after illumination. Photocurrent decay as a function of time was exponential for short time periods (i.e. for milliseconds), while for longer periods it was described by the power function t$\text{}^{-1/l}$, where parameter 1 is the characteristic parameter of the exponential distribution of traps.