In tandem-structured dye-sensitized solar cell (DSSC) composed of two parallel-connected sub-cells, the photovoltage (V oc ) generated by the back sub-cell is usually rather low, resulting in low V oc and conversion efficiency (Γ) of the tandem cell. To solve this issue, two simple but very efficient strategies, namely, the filling of Li + -absent electrolyte and/or coating Al 2 O 3 on TiO 2 electrode surface in the back sub-cell, were explored to enhance the V oc of the back sub-cell and hence that of the tandem cell. The former strategy was expected to heighten the energy level of TiO 2 conduction band, and the latter one to retard the charge recombination. The photovoltaic performance measurements reveal that in the both cases, although there was a slight decrease in the photocurrent (J sc ), an obvious rise in the V oc was achieved for the tandem cells, leading to significant improvements in Γ of the tandem cells. Compared to the individual organic dyesensitized solar cell (the highest Γ is 7.58%), the tandem cell with two organic dyes having complementary absorption spectra demonstrates an improved efficiency of up to 8.33% by a combinational application of Li + -absent electrolyte and Al 2 O 3 overcoat. The results presented in this study highlight that the efficiency of a parallel-connected tandem-structured DSSC can be improved significantly through enhancing the photovoltage of the back sub-cell, which is first time reported.