Physics underlying the performance of back-surface-field solar cells

A description of the physics of back-surface-field (BSF) solar cells is presented, in which several key approximations, valid for effective BSF cells, have been used to express the results of the analysis in ways that make them useful in understanding the performance of high-efficiency BSF cells. A silicon p⁺-n-n⁺BSF solar cell, developed in conjunction with the theoretical treatment, provides experimental support for the theory. Measured current-voltage characteristics, together with the analysis, are used to describe the important physical mechanisms that control the performance of the BSF solar cell. For example, the analysis enables the determinations of the carrier lifetimes in the base region and of the effective surface recombination velocity at the low-high junction.