Dynamics of photoinduced charge transfer between pentacene and a C-60-terminated self-assembled monolayer

A C-60-terminated self-assembled monolayer can be used to place molecular acceptor states at the interface between the semiconductor and gate insulator of an organic field effect transistor. The time dependence of the photoinduced charge transfer between pentacene and C-60 has a fast component with a characteristic time of 1.9 s and slower component with a time constant of 32 and 48 s at the beginning and end of a transient increase in illumination, respectively. Variation in the threshold voltage shift with the thickness of the pentacene results from the competing length scales for light absorption and exciton diffusion.