23327Enhanced photoelectric conversion efficiency of dye-sensitized solar cells by the incorporation of flower-like Bi(2)S(3):Eu(3+) sub-microspheres

In this paper, TiO(2)-Bi(2)S(3) and TiO(2)-Bi(2)S(3):Eu(3+) composite photoanodes were successfully designed, which can not only fully absorb visible light but also transfer the electron from Bi(2)S(3) to TiO(2) conduction band due to the narrow band gap and high conduction band of Bi(2)S(3). Compared to pure TiO(2) cell, the photoelectric conversion efficiencies of TiO(2)-Bi(2)S(3) and TiO(2)-Bi(2)S(3):Eu(3+) composite cells were increased significantly. In addition, the efficiency of TiO(2)-Bi(2)S(3):Eu(3+) composite cells were higher than that of TiO(2)-Bi(2)S(3) cell which could be attributed to the larger BET surface area of Bi(2)S(3):Eu(3+). The electron transport and interfacial recombination kinetics were investigated by the electrochemical impedance spectroscopy and intensity-modulated photocurrent/photovoltage spectroscopy. The results indicated that the interfacial resistance of the TiO(2)-dye|I(3)(−)/I(−) electrolyte interface of TiO(2)-Bi(2)S(3):Eu(3+) composite cell was much bigger than that of pure TiO(2) cell. In addition, the TiO(2)-Bi(2)S(3):Eu(3+) cell has longer electron recombination time and longer electron transport time than pure TiO(2) cell. The charge collection efficiency of TiO(2)-Bi(2)S(3):Eu(3+) composite cell was higher than that of pure TiO(2) cell.