Modification of TiO2 heterojunctions with benzoic acid derivatives in hybrid molecular solid-state devices

Abstract

The organic-inorganic heterojunction of TiO2 with the new hole conducting material modified via surface adsorption of para-substituted benzoic acids with different dipole moments was studied. Organic molecules such as para-functionalized benzoic acids can be used to systematically modify current-voltage characteristics of organic-inorganic heterojunctions. These results were shown to be consistent with the variation in the work-function of the modified TiO2, measured on the free surface. This effect is attributed to a change in the band bending at the TiO2 spiro-(2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenylamine) -9,9′spirobifluorene) interface induced by the dipole moment of the adsorbed benzoic acids.