Composition and structural study of solution-processed Zn(S,O,OH) thin films grown using H₂O₂ based deposition route

Recent results have revealed that the low deposition time issue of chemical bath deposited (CBD) Zn(S,O,OH) buffer layer used in Cu(In,Ga)Se₂ (CIGSe) solar cells could be resolved using H₂O₂ as an additive in the chemical bath solution. Although the use of this additive does not hinder the electrical properties of the resulting Zn(S,O,OH)-buffered CIGSe solar cells, the impact of H₂O₂ on the Zn(S,O,OH) properties remains unclear. The present contribution aims at determining the chemical composition and the microstructure of Zn(S,O,OH) film deposited by CBD using the alternative deposition bath containing the standard zinc sulfate, thiourea, ammonia but also H₂O₂ additive. Both X-ray photoemission spectroscopy and energy dispersive X-ray spectroscopy analyses reveal higher sulfur content in alternatively deposited Zn(S,O,OH), since the first step growth of the layer. According to transmission electron microscopy analyses, another consequence of the higher deposition rate achieved when adding H₂O₂ in the bath is the modification of the absorber/buffer interface. This could be explained by the enhancement of the cluster growth mechanism of the layer.