Many-body theory applied to solar cells: excitonic and related carrier correlation effects

The independent electron theory of semiconductors was developed in the early 1930s, with the modern theory of semiconductor devices established over the subsequent decades. Increasingly comprehensive device simulators, improvements in material properties and the evolution in device design are starting to thoroughly test this theory. The present paper discusses many body effects in solar cells including room temperature excitons and other correlation effects together with their consequences. It is shown that, at moderate to high doping levels, excitonic and other correlated carriers can approach uncorrelated minority carrier concentrations, casting doubts over the adequacy of existing theory based solely on minority carrier flows to satisfactorily model effects such as back surface fields and built-in fields in solar cell emitters