Periodic density functional theory study on the interaction mode and mechanism of typical additives with TiO2 substrates for dye-sensitized solar cell applications

Abstract Five typical additives N -Butylbenzimidazole (NBB), N -Methylbenzimidazole (NMBI), 3-Methoxypropionitrile (MPN), 4- tert -butylpyridine (TBP) and Guanidinium thiocyanate (GNCS) are selected to investigate the diverse interactions with TiO 2 anatase (101), (100) and (001) surfaces in vacuum and acetonitrile conditions, respectively, by means of the analyses of adsorption mode and electronic structure based on a periodic density functional theory method. Five additives are adsorbed more strongly in the order (101)  2 (001) surface induced by additive adsorption affect bonding greatly. GNCS possesses the maximum adsorption energy due to special multidentate and dissociative adsorption modes, while MPN has the minimum adsorption energy, no matter which surface is used. Positive Fermi energy shift (i.e. negative potential shift) is in the order (100)  2 (100) and (001) systems. There should be a critical point of adsorption density for MPN and TBP adsorption on the TiO 2 (100) and (001) surfaces, changing Fermi energy shift from negative to positive value.