Electrochemical investigation of Li+ ions in the electrolyte on the performance of dyed Mg2+-doped TiO2 solar cells

• The doped Mg ions as a major recombination channels in dyed Mg2+-doped TiO2 solar cells with Li+ electrolyte.
• The increase in IPCE at long wavelengths for DSCs with increasing Li+ concentration in the electrolytes.
• The improved stability of dyed Mg2+-doped TiO2 solar cells with LiI electrolyte under room temperature.

This work mainly studies the effect of Li+ ions in the electrolyte on the enhancement of photoelectric performance and stability in the dyed Mg2+ doped TiO2 solar cells. Measurements of dynamic recombination between interface electron lifetime τn and short-circuit current Jsc suggested that the doped Mg ions as recombination channels, rather than Li+ ions, played key role in recombination reaction in Mg2+-doped TiO2 electrodes. The adsorbed Li+ on the surface of Mg2+ doped TiO2 is mainly attributed to the positive shift of the conduction band edge that resulted in the decreased Voc. It is found that the conduction band edge of Mg2+ doped TiO2 electrodes was positively shifted with the increasing concentration of Li+ from 0 M to 0.4 M, which led to the increases of the electron injection efficiency ηinj and the photocurrent density Jsc for Mg2+ doped TiO2 solar cells. And the stability of Mg2+ doped in solar cells showed that the adsorbed and intercalated Li+ ion in Mg2+ doped TiO2 electrode can improve the cell performance and interface stability.