Abstract
Limited efficiency of Cu2ZnSnS4 (CZTS) solar cells due to high recombination rates at the CZTS-buffer interface calls for alternative buffer materials to enhance the open circuit voltage and, therefore, the device performance. By means of ab-initio hybrid functional calculations, the authors investigate the interfaces between the p-type absorber CZTS and the n-type buffer materials Al2ZnO4, CeO2, or ZnSnO3 to evaluate the band alignment. Strong hole confinement is predicted for the CZTS/Al2ZnO4 and CZTS/ZnSnO3 interfaces. A small conduction band offset of 0.31 eV is obtained for the CZTS/ZnSnO3 interface, indicating that ZnSnO3 should be considered for improving the efficiency of CZTS solar cells.