Synthesis of 2-amino-4-(4-(methylamino)phenyl)-6-phenylnicotinonitrile as a new additive for the passivation of the TiO2 surface and retarding recombination in dye-sensitized solar cells

In this research, we synthesized a phenylnicotinonitrile derivative as a new type of additives and studied its effect on the performance of dye-sensitized solar cells by UV-Vis spectroscopy, cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In comparision with a blank electrolyte (0.35 M lithium iodide, 0.035 M iodine and 0.01 M guanidium thiocyanate in a much less leakage and volatile solvent such as propylene carbonate, PC-liquid), addition of 0.5 M phenylnicotinonitrile derivative caused an increase in the open-circuit potential (Voc) of 209 mV but a decrease in the short current density (Jsc) of 3.36 mA/cm2. The increase could be attributed to the negative shift of the conduction bond of TiO2 semiconductor potential (Voc, ∼34% of the voltage increase) and to the increase of the photo-conversion efficiency (PCE, ∼21% of the efficiency increase). The decrease in Jsc was because of the reduction of dye regeneration and the catalytic activity of the photocathode in electrolyte regeneration. It was shown that the fabricated dye-sensitized solar cells (DSSCs)-based different electrolytes displayed the relative standard deviation (RSD) range of 3.24%-4.36% for six repetitive measurements (n = 6).