Effects of an Intercalation Nanocomposite at the Photoanode/Electrolyte Interface in Quasi-Solid Dye-Sensitized Solar Cells

In this paper, interface effects of N-methyl-benzimidazole (NMBI) and a novel intercalation composite of NMBI and montmorillonite (MMT) were studied. The intercalation composite showed better interface modification effects than NMBI individually. The FTIR spectra results showed interaction between N3 and NMBI could retard the aggregation of dye molecules, decreasing the electron quenching and charge recombination. However, the results of cyclic voltammograms and UV-vis absorption edge revealed the interaction between NMBI and dye molecules could cause the lowest unoccupied molecular orbital (LUMO) level of the dye molecule to drop, decreasing the electron injection efficiency. It decreased the J(sc) of dye-sensitized solar cells (DSCs). The intercalation composite could remedy the disadvantage of NMBI and obtain strengthened interface effects. The photocurrent-voltage (I-V) curve showed that, with the modification of this intercalation nanocomposite, the J(sc) of the devices increased, showing that the disadvantage caused by NMBI was improved. Besides, results of the dark current curve and transient photovoltage spectra showed the NMBI-MMT intercalation composite modification retarded charge recombination more effectively than using NMBI individually. An electrochemical impedance spectroscopy (EIS) test also indicated that modification of the NMBI-MMT intercalation composite showed a strengthened effect of retarding the charge recombination. Furthermore, the results of intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) tests also showed that the interface modification of the NMBI-MMT intercalation composite enhanced the electron transportation and lifetime in DSCs more than using NMBI individually.