Analytical Models of Bulk and Quantum Well Solar Cells and Relevance of the Radiative Limit

摘要

The analytical modelling of bulk and quantum well solar cells is reviewed.The analytical approach allows explicit estimates of dominant generation andrecombination mechanisms at work in charge neutral and space charge layers ofthe cells. Consistency of the analysis of cell characteristics in the light andin the dark leaves a single free parameter, which is the meanShockley-Read-Hall lifetime. Bulk PIN cells are shown to be inherentlydominated by non-radiative recombination as a result of the doping relatednon-radiative fraction of the Shockley injection currents. Quantum well PINsolar cells on the other hand are shown to operate in the radiative limit as aresult of the dominance of radiative recombination in the space charge region.These features are exploited using light trapping techniques leading to photonrecycling and reduced radiative recombination. The conclusion is that themirror backed quantum well solar cell device features open circuit voltagesdetermined mainly by the higher bandgap neutral layers, with an absorptionthreshold determined by the lower gap quantum well superlattice.