An extended model of upconversion based solar cells

An upconversion-based solar cell (UCSC) consists of a bifacial solar cell coupled to a spectral upconverter. This configuration has been suggested as a means of achieving solar cell efficiency beyond the Shockley-Queisser limit. In this paper an extended model of a UCSC is presented. This model adds to the capabilities of previously-reported models by considering a) non-radiative recombination; b) different anti-reflection (AR) layers at the air-solar cell and solar cell-upconverter interfaces; and c) dissimilar refractive indices of the solar cell and upconverter. Results obtained by analyzing the effect on efficiency of the solar cell band gap, location of intermediate excited state, amount of relaxation of electrons in the intermediate band, solar cell and upconverter refractive indices, and presence or absence of antireflection coatings between the air-solar cell and solar cell-upconverter interfaces, are presented.