Photocharacteristics for Electrolyte‐Semiconductor Junctions

The electrolyte‐semiconductor junction has lately received considerable attention as a half‐cell electrode to be used with or without illumination. In spite of the activity in this field very little has been done toward deriving the electrical photocharacteristics based on the transport of carriers and the quantitative treatment of junction potentials. In this paper we attempt to remedy the situation by setting down the logic underlying the problem and undertaking the derivation of the photocharacteristics, in terms of various phenomenological transport and kinetic coefficients, for a number of fairly realistic systems. Our purpose is not to be exhaustive but to illustrate the process of derivation so that the reader will be able to extend it to other particular systems of interest. When possible we show the relation of our results to previous analyses (in the few cases where they exist). This comparison identifies the condition under which some of the previous results are valid. We have tried to be as critical as possible. Among the effects included in our model are those due to Guoy layers, redox systems, overvoltage, surface recombination, and hole‐electron transport and recombination in the bulk of the semiconductor.