Suns-photoluminescence: Contactless determination of current-voltage characteristics of silicon wafers

Abstract

In good silicon solar cells, the separation of the quasi-Fermi energies $\Delta \eta$ in the bulk is equivalent to the cell voltage. Photoluminescence is used to measure $\Delta \eta$ in both bifacial solar cells and partly processed solar cells. The bifacial cells are used to demonstrate that simultaneous measurement of the photoluminescence signal and of the variable incident light intensity yields pseudo current-voltage characteristics, equivalent to Suns-open circuit voltage $\left(V_{\mathrm{OC}}\right)$ measurements, but in contactless mode. The applicability of this method to unfinished solar cells, without the need for a solar cell structure, is demonstrated on silicon wafers after various processing steps.