Small molecular organic photovoltaic cells with exciton blocking layer at anode interface for improved device performance

We demonstrate enhanced power conversion efficiency (eta(PCE)) for small molecular-based organic photovoltaic cells with an exciton blocking layer (ExBL) at the anode/donor interface. Although poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) films are widely used as anodic buffer layers, they also act as exciton quenchers. To prevent exciton quenching, we introduced a tris[4-(5-phenyl thiophen-2-yl)phenyl]amine layer between the donor and the PEDOT:PSS layer and clarified its effect. By a combination of dual ExBLs at both the anode and cathode sides, we achieved significantly enhanced short circuit current and eta(PCE) values; the highest eta(PCE) = 5.24% was obtained by optimizing the device parameters. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3650472]