23327Enhanced photoelectric conversion efficiency of dye-sensitized solar cells by the incorporation of flower-like Bi2S3: Eu3+ sub-microspheres

In this paper, TiO2-Bi2S3 and TiO2-Bi2S3: Eu3+ composite photoanodes were successfully designed, which can not only fully absorb visible light but also transfer the electron from Bi2S3 to TiO2 conduction band due to the narrow band gap and high conduction band of Bi2S3. Compared to pure TiO2 cell, the photoelectric conversion efficiencies of TiO2-Bi2S3 and TiO2-Bi2S3: Eu3+ composite cells were increased significantly. In addition, the efficiency of TiO2-Bi2S3: Eu3+ composite cells were higher than that of TiO2-Bi2S3 cell which could be attributed to the larger BET surface area of Bi2S3: Eu3+. 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 TiO2-dye|I-3(-)/I- electrolyte interface of TiO2-Bi2S3: Eu3+ composite cell was much bigger than that of pure TiO2 cell. In addition, the TiO2-Bi2S3: Eu3+ cell has longer electron recombination time and longer electron transport time than pure TiO2 cell. The charge collection efficiency of TiO2-Bi2S3: Eu3+ composite cell was higher than that of pure TiO2 cell.