Abstract
The ultrathin SnO2 film, prepared by the successive ionic layer adsorption and reaction (SILAR) method, was applied between p-type Cu2ZnSnS4 (CZTS) and n-type CdS layers to passivate the interface as well as the top section of CZTS grain boundaries. With the aid of this layer, electric properties have been significantly improved. The device efficiency improved from 6.82% to 8.47%, which is mainly contributed by the boost of fill factor (FF) and open circuit voltage (V-oc). However, the further increase of SnO2 thickness results in decreased J(sc) and FE Kelvin Probe Force Microscopy (KPFM) unveils the passivation of grain boundaries (GBs) of CZTS with the SnO2 coating. This work shows a new insight into the heterointerface and GBs passivation for high efficiency CZTS solar cells.