Numerical simulation about effects of bandgap grading in Cu(In, Ga)Se2 with a bandgap of 1.4 eV on solar cell performance

The effects of bandgap grading in a Cu(In, Ga)Se
₂
thin film with the average bandgap of 1.4 eV on the performance of the solar cells were investigated by changing a minimum bandgap and its position employing wxAMPS. Considering minority carrier recombination at the CdS/CIGS interface, degradations of solar cell characteristics were observed. In this case, double graded band profile is required in order to suppress the recombination. However, considering also an ordered vacancy compound (OVC) at the interface, a high efficiency that is close to the case without interface recombination was obtained. These results indicate that the field effect passivation owing to OVC can suppress the interface recombination.