Band offsets of Ag2ZnSnSe4/CdS heterojunction: An experimental and first-principles study

Band offsets at the interface of the Ag2ZnSnSe4 (AZTSe)/CdS heterojunction were systematically investigated by combining experiments and first-principles calculations. For the AZTSe/CdS interface, a higher conduction-band minimum (CBM) of the CdS than that of the AZTSe was found and the conduction-band offset of 0.31 eV was determined using X-ray photoelectron spectroscopy. Theoretically, we constructed the AZTSe/CdS interface and calculated the band alignments. Two different configurations were adopted in the calculations: the AZTSe/CdS superlattice and the AZTSe/CdS heterojunction with a vacuum layer. The calculated results indicate that CdS has a higher CBM than AZTSe at the AZTSe/CdS interface, well supporting the experimental results. Our results suggest that the AZTSe/CdS heterojunction has an ideal band structure for photovoltaic applications.