Improved performance of dye-sensitized solar cells with novel conjugated organic dye using aluminum oxide-coated nanoporous titanium oxide films

摘要

This work introduces the TiO_2/dye/electrolyte interface in the recombination and offers an interface treatment method using solution process for dye-sensitized solar cells (DSSCs). Solution-processed ultra-thin metal oxides introduce to treat the surface of mesoporous TiO_2 to reduce the defect density and improve the electronic quality. Among the metal oxides, an Al_2O_3 barrier is incorporated into DSSCs as a carrier-recombination blocking layer. In all instances, the short-circuit current density increase and the dark current is suppressed after Al_2O_3 deposition. The impact of the Al_2O_3 barriers is also studied in devices employing different dyes. To compare the behavior of metal-free organic dyes and Ru dyes when Al_2O_3 barrier layers are involved, the charge transfer between the dye and TiO_2 electrodes, associated with interfacial electron injection, is investigated by Raman spectroscopy. The metal-free organic dye had a high molar extinction coefficient and better adsorption properties compare to Ru dye, which resulted in higher charge-collection efficiency. To verify the strategy, the DSSCs photovoltaic performances containing these dyes are compared using their current-voltage curves. Electrochemical impedance spectroscopy (EIS), Intensity Modulated Photocurrent Spectroscopy (IMPS), and Intensity Modulated photoVoltage Spectroscopy (IMVS) were used to further investigate the kinetics process of the TiO_2 film electrodes.