The Effect of Exchanging the ZnO and CuO layers on the performance of solar cells

Abstract

In this work two solar cells types were fabricated. The first type is (FTO/CuO/ZnO/Al) and the second type is FTO/ ZnO/ CuO/Al. Six samples were prepared from each type. The efficiency for each type was obtained. It was found that the efficiency of FTO/ZnO/CuO/Al is in the range ~0.6×10-3, while the efficiency of FTO/CuO/ZnO/Al is in the range ~2×10-3 the difference may be attributed to the fact that FTO and CuO acts as P-type semiconductor, while ZnO act and n-type semiconductor. Thus the first type acts as PnP component that has a low efficiency, while the second type acts as PPn component and has relatively high efficiency. The energy gaps for CuO and ZnO are obtained by using optical absorption and transmittance spectra the optical absorption for CuO and ZnO shows a peak corresponding to the energy gaps in the ranges (1.3 – 2 eV) and (2.2-3.6eV) respectively. These values are compatible with the observed values in other studies, these values measure acceptor and donor levels For CuO and ZnO, however the transmittance spectrum for CuO and ZnO, shows band gaps about Eg~3.7eV and 3.6 EgeV. These values measure the energy gap between conduction and valence band for both, respectively.