High efficiency Cu2ZnSnS4 solar cells over FTO substrates and their CZTS/CdS interface passivation via thermal evaporation of Al2O3

Abstract

The fabrication of soda lime glass/fluorine-doped tin oxide (SLG/FTO) transparent substrates represents an important advance in the fabrication of tandem solar cells. In addition, possible passivation using Al₂O₃, which can be deposited using cheap systems, can open up the development of Cu₂ZnSnS₄ (CZTS) solar cells. In this work, we report the simultaneous use of FTO/Mo (20 nm) as a transparent substrate and Al₂O₃ as apassivation layer at the p–n interface in CZTS solar cells. The best devices show efficiencies of 7.7% (V_oc = 677 mV) and 7.3% (V_oc = 700 mV). Complete analysis, in terms of morphology, structure and electrical properties, is discussed.