Optical improved structure of polycrystalline silicon-based thin-film solar cell

This paper presents an n-i-p type solar cell structure consisting of polycrystalline silicon thin film as an absorber of incident radiation and a ZnO thin film for optical improvement. The characteristics of Si layers (thickness and doping level) are designed to assure a high value of collection efficiency for photogenerated carriers. The thin films of polycrystalline silicon are obtained by CVD at a temperature of around 620°C. ZnO thin film is prepared by thermal decomposition of Zn-acetylacetonate [Zn(C5H7O2)2] in a vertical reactor. It is used as AR coating and as contact electrode due to its properties of high transparency (>90%) and high conductivity (3×10−4 Ω cm). Polycrystalline silicon and ZnO films have been investigated in terms of surface morphology and grain size by AFM and XRD.