Exciton Diffusion in Multilayer Thin-Film Pentacene/C 60 Photovoltaic Cells: Modeling of Spectral Response
Seunghyup Yoo, William J. Potscavage Jr., Benoit Domercq and Bernard Kippelen
A model describing exciton diffusion is used to describe the spectral response of multilayer organic photovoltaic cells based on pentacene/C60 thin film heterojunctions. The electric field distribution inside a cell is calculated from the complex optical constants of the layers that comprise the cell. Exciton diffusion lengths are estimated in pentacene and C60 by using this model to fit the spectrum of the external quantum efficiency of charge generation. A large exciton diffusion length of ca. 50 –70 nm is found for pentacene.