An experimental investigation of temporal instability in high resistivity silicon solar cell performance

The authors report a time-dependent change in the cell parameters of silicon solar cells made on p-type, high-resistivity (20-30 Omega -cm) base material. Solar cells from three different manufacturers were investigated, and marked changes in V/sub oc/, I/sub sc/, and P/sub m/ were observed under illumination. From V/sub oc/(t) measurements under different conditions, it appears that the observed phenomenon is due to recombination centers located in the bandgap near the conduction band edge. These are probably generated during the alloying of aluminum on the back surface of the cells. Spectral response measurements made before and after shining the light show a reduction in the long wavelength response, indicating a bulk phenomenon. The observed instability can have an important bearing on the matching of cells in module making.<>