Enhancing performance of organic–inorganic hybrid solar cells using a fullerene interlayer from all-solution processing

Quality of the interface between organic and inorganic nanostructures is critical for the performance of the organic–inorganic hybrid device based on a blend of the polymer:fullerene and the ZnO nanorod array. We investigated the effect of a solution-processed interlayer on such device performance. A fullerene interlayer was spin-coated onto the ZnO nanorod surface to modify ZnO nanorod interface. The power conversion efficiency (PCE) was improved from 2.35% to 3.2%, with a short-circuit current density of 11.67 mA/cm2, an open-circuit voltage of 0.55 V, and a fill factor of 0.5 under 100 mW/cm2 irradiation. Our investigations show that this improvement is caused by the enhanced optical absorption because this fullerene interlayer helps the polymer to self-organize and improves the infiltration of the photoactive layer into ZnO nanorod spacing. As a result, the internal series resistance is reduced, thus increasing the photocurrent and the PCE.