Photoconductive properties of zeaxanthin in a sandwich cell

Abstract

Photoconduction decay in zeaxanthin in a sandwich cell has been measured as a function of applied field and temperature in longer time domains (5-35 s). The results show that the gap states decrease exponentially with characteristic temperature T, ,~, 450 K at an applied field of 1.77 • 103 V/cm. When the sample temperature is 293 K, T, is found to be voltage-dependent and follows the empirical relation T, ,~, A exp(-b 1I). "l~e field effect on T~ is suggested to arise from the field effect on trapping rate. Light intensity dependence of photocurrent satisfies the power law I~, oc 1~ with y varying between 0"61 and 0-58 depending on the applied voltage at low excitation light intensity. At high intensities ~, = 1'2. 7", values evaluated from decay and light intensity dependence measurements show excellent correlation.