Promising Sb-2(S,Se)(3) Solar Cells with High Open Voltage by Application of a TiO2/CdS Double Buffer Layer

Sb-2(S,Se)(3) has gathered a lot of attention recently as a promising alternative absorber material. However, the efficiencies of Sb-2(S,Se)(3) devices are seriously restricted by the low open circuit voltage (V-oc). In this work, Sb-2(S,Se)(3) devices equipped with a TiO2/CdS double buffer layer are prepared by a hydro-thermal method, which aims to overcome the V-oc deficit. The obtained average V-oc of the devices is 785 mV and the champion efficiency of 5.73% is also achieved with a highest V-oc = 792 mV, Jsc = 12.03 mA cm(-2), FF = 60.9%. The improvement of V-oc is benefited from the reduced band gap offset after application of the double buffer layer. The non-encapsulated device could keep an average power conversion efficiency of 5.69% after being stored in ambient air over a month. This indicates the great potential of a double buffer layer in new chalcogenide photovoltaic devices.