Investigation of Non-Ohmic Properties for Thin Film InGaP/GaAs Solar Cells

An efficient, flexible and lightweight thin-film InGaP/GaAs solar cell has been developed. We discovered a reduction in open-circuit voltage (Voc) of the thin-film InGaP/GaAs cell due to the non-ohmic characteristics in the interface between the metal film and p-type contact layer on the rear of the cell. Additionally, the non-ohmic characteristics influenced the temperature coefficient of Voc. Cells with 2.34 V and 2.08 V Voc were evaluated in this investigation. The difference in Voc was caused by a difference in carrier concentration of the layer which contacts thin metal film on the rear of the cell. These results indicate that the reduction in Voc of the thin-film cell is due to an opposite voltage generated in the interface between the contact layer and the metal film. The characteristics were improved by introducing a tunnel junction into the interface. Good ohmic characteristics in the interface between the rear of the thin-film cell and the metal film is required for improving efficiency