Effect of Mg Doping on SnO2 Energy Band and Power Conversion Efficiency of Dye-Sensitized Solar Cells

Abstract

In this work, Mg-doped SnO2 materials with different molar ratios were synthesized by hydrothermal method. Based on the UV-Vis study, band gap (Eg) of the Mg-doped SnO2 is adjusted from 3.76 eV to 3.65 eV via 3 at% concentrations. Results of photovoltaic measurement for dye-sensitized solar cells (DSCs) based on Mg-doped SnO2 film as photoanode indicate that the doping of Mg ions can improve the open-circuit voltage (V oc) of the DSCs, while the electric current density (J sc) of the DSCs is almost unchanged. The cells were measured at 3 days intervals within 24 days after fabrication. Power conversion efficiency (PCE) of 3 at% Mg-doped SnO2 DSCs increases step by step and achieves 4.38% as the cell is tested after 18 days. Electrochemical impedance spectroscopy (EIS) analysis shows that Mg doping enhances light collection, increased the number of photogenerated electrons and inhibits charge recombination.