Fabrication of FTO/Li2O/ZnO/p-PSi/Al solar cell by chemical precipitation method

Abstract

In this paper, electrochemical etching of the p-type silicon wafer is used to prepare p-type porous silicon with a current density of 10 mA.cm-2 for 10 minutes. Zinc oxide and lithium oxide nanoparticles are prepared separately by chemical precipitation method and simple precipitation method respectively and deposited on glass substrates by drop-casting method. Moreover, the structural and optical properties of the films were analyzed by using XRD and UV-Vis. The XRD results showed that the ZnO and Li2O films are polycrystalline with hexagonal wurtzite structure and cubic structure, and preferred orientation along (101) and (003) planes, respectively. Using Scherrer's formula, the crystallite size was measured and it was found that ZnO and Li2O thin films have a crystallite size of 22.04 and 45.6 nm respectively. The atomic force microscope image and the distribution chart of the grains of the ZnO and Li2O films displayed the grain sizes of~ 58.45 and 83.19 nm. The absorption coefficient spectrum of films were recorded by Ultra Violet–Visible spectrophotometer. The energy band gaps of the films calculated by Tauc’s formula were ~ 4.18 and 5.5 eV. The results demonstrated that the conversion efficiency for Al/Li2O/ZnO/p-PSi/Al, Al/Li2O/ZnO/FTO and FTO/Li2O/ZnO/p-PSi/Al tandem (porous silicon/FTO) solar cells were 0.313%, 0.764% and 24.6%.