2-(4-Fluorophenyl)-1-methyl-d3-1H-benzo[d]imidazole is the labeled analogue of 2-(4-Fluorophenyl)-1-methyl-1H-benzo[d]imidazole (F595635), which has been used as an electrolyte additive used to enhance the performance of dye-sensitized TiO2 solar cells.