Theoretical band alignment in an intermediate band chalcopyrite based material

- Theoretical band alignment of chalcopyrite thin film solar cell heterojunctions.
- Theoretical study of an intermediate band material.
- Good agreement between theoretical and experimental results for bulk materials.
- Theoretical band alignments proposal for the design of an intermediate band solar cell.

Band alignment is key to enhance the performance of heterojunction for chalcopyrite thin film solar cells. In this paper we report ab initio calculations of the electronic structures of CuGaS2:Cr with various Cr compositions, CuAlSe2 and ZnSe and the band alignment between their interfaces. We use density functional theory and the more accurate self-consistent GW scheme to obtain improved bulk band-gaps and band offsets. Band alignments of the interfacial region for CuGaS2:Cr/CuAlSe2 and CuGaS2:Cr/ZnSe systems were aligned with respect of an average electrostatic potential. Our results are in good agreement with experimental values for the bulk band-gaps. These theoretical band alignments show a characteristic staggered band alignment for the design of heterojunction devices in photovoltaic applications.