Photovoltaic properties of Cu2ZnSnS4 cells fabricated using ZnSnO and ZnSnO/CdS buffer layers

To improve the photovoltaic properties of Cu2ZnSnS4 (CZTS) photovoltaic cells, we investigated the use of novel buffer layer materials. We found that Zn1-xSnxOy fabricated by atomic layer deposition functioned as an effective buffer layer. The short-circuit current density increased by 10% because of a decrease in the absorption loss in the short-wavelength region. With Zn0.70Sn0.30Oy layers, the conversion efficiency was 5.7%. To reduce interface recombination, a thin CdS layer was inserted between the ZnSnO and CZTS layers. The CZTS cells fabricated using ZnSnO/CdS double buffer layers showed a high open-circuit voltage of 0.81 V. (C) 2016 The Japan Society of Applied Physics