A General Model for Surface Junction Solar Cells

A general analysis is developed for the effects of illumination and surface recombination on the currents flowing in a semiconductor / conductor junction. The analysis provides correct interpretation of the role of surface states on the efficiency of the solar cell. As will be shown in this paper, earlier models for the solar cells employ a basic assumption about surface state recombination which is contradictory with the other assumptions employed in the model. The contradiction disappears only under restricted and unrealistic conditions. The two theories describing the currents in a Schottky barrier junction, the thermionic emission theory and the diffusion theory of Shockley are shown to have their parallels in a semiconductor / electrolyte contact. A Shockley-Read-Hall model for surface recombination was employed in the analysis and it is shown that the results of this model reduce to the expressions often used in the literature under certain conditions.