Thermal behavior of crystalline thin film silicon solar cells

The goal of this paper is to investigate the thermal behavior of crystalline thin film silicon solar cells, and to determine whether the decrease in cell thickness affects the temperature dependences of the solar cell parameters. For the investigation crystalline solar cells with a photoactive layer thickness of 26, 38 and 50 microns were used. Sample cells were formed on n+-substrate wafers with n epitaxial layers where due to the low minority carrier lifetime in the substrate only the epitaxial layer participates effectively in the photocurrent generation. The thin photoactive layers were achieved by the etching of the epitaxial layer. On the samples I-V curves and spectral response functions were measured at different temperatures, and the temperature coefficients of the short circuit current, the open circuit voltage and the efficiency were determined. It was found, that the short circuit current shows higher temperature dependence in thin crystalline silicon cells, than in silicon solar cells with the usual thickness (150-200 μm). An explanation for this effect can be given based on the temperature dependence of the absorption factor of crystalline silicon. The results of the temperature dependant spectral response measurements seem to confirm this proposition.