One-step Sn4+-based anodic deposition for flattening of fluorine-doped tin oxide enabling large transmittance enhancements

A novel, facile, one-step Sn4+-based anodic deposition method was developed to flatten fluorine-doped tin oxide (FTO) layer, leading to a significant enhancement in visible light transmittances, from 79 to 85%. The Sn2+ necessary for the anodic deposition of SnO2 was generated in situ from the starting Sn4+ such that a slow and balanced deposition and acid-etching of SnO2 became possible. Furthermore, the fluoride ions released from the acid-etching of the starting FTO layer were later incorporated into the newly deposited SnO2 to make it fluorine-doped, giving rise to the formation of the conductive, much flattened FTO layer. The flattening of the FTO layer led to a significant light scattering reduction at the FTO-air interface and thus enhanced the light transmittances.