Interdigitated Back Contact Solar Cells. Annual Report

摘要

The interdigitated back-contact solar cell (IBC cell) has been shown to possess a number of advantages for silicon solar cells, which operate at high concentration. The purpose of the present program is to support the Sandia Laboratory effort to optimize the IBC cell. A detailed discussion of the factors which need to be considered in the analysis of semiconducting devices which utilize heavily doped regions such as those which are found in solar cells in both the emitter and in the back surface field regions is given. This discussion covers the questions of: how to handle degeneracy, how to compute carrier concentrations in the absence of knowledge of the details of the band structure under heavily doped conditions, how to reconcile the usual interpretation of heavy doping as a rigid shift of the bands with the band tailing and impurity level conduction models. It also discusses the reasons for the observed discrepancy between various experimental measurements of bandgap narrowing. A discussion of the appropriateness of using experimentally determined parameters in conjunction with degenerate statistics in calculating cell performance is also presented. A detailed discussion of the one dimensional formulation of the solar cell analysis as well as a description of the one dimensional programs which have been writtten to perform this analysis are included. The results of calculations using the one dimensional program to analyze typical situations which occur in high intensity conventionally designed silicon solar cells are presented. (ERA citation 05:034647)