Improved power conversion efficiency in bulk heterojunction organic solar cells with radial electron contacts.

We incorporate radial electrical contacts penetrating a blended organic semiconductor active layer to shorten the electron collection pathway in poly(3-hexylthiophene):[6,6]-phenyl-C(61)-butyric acid methyl ester bulk heterojunction solar cells and simultaneously confine the blend material within nanometer-scale volumes. This architecture improves the active material performance by more than 50% compared to its performance in a bulk heterojunction with planar contacts, consistent with accelerated electron extraction. The radial contact solar cell achieves similar overall photovoltaic power conversion efficiency to control bulk heterojunction devices with planar contacts, despite containing less than half the volume of light-absorbing semiconductor material.