Impact of Cu-deficient p-n heterointerface in CuGaSe2 photovoltaic devices

It is expected that Cu-deficient phases of chalcopyrite CuGaSe2 (CGS), such as CuGa3Se5, will be used widely as functional materials in energy conversion devices. In this study, the effect of a Cu-deficient CGS layer (CDL) at the p-CGS/n-CdS interface was investigated. The presence of the CDL was found to have a significant effect on increasing the open-circuit voltage (V-oc) of CGS photovoltaic devices. This result is contrary to the results obtained for CuInSe2 (CIS) and Cu(In,Ga)Se-2 (CIGS) devices, which showed a decrease in V-oc with the increasing CDL thickness. It was also found that the use of a thicker n-CdS layer is effective in increasing the short-circuit current density (J(sc)) and V-oc for CGS devices fabricated with a thick CDL. These trends are unique to CGS devices and are, thus, expected to offer unique and specific routes for improving wide-gap chalcopyrite photovoltaic device performance, in addition to offering a conventional strategy for adjusting the conduction band alignment of the p-CGS/n-buffer interface with proper n-buffer materials.

Automated summary

The study found that the presence of Cu-deficient phases in chalcopyrite CuGaSe2 significantly increases the open-circuit voltage of photovoltaic devices. Additionally, using a thicker n-CdS layer can effectively improve the short-circuit current density and open-circuit voltage in CGS devices with a thick Cu-deficient layer, offering unique routes for enhancing device performance.