Thin pentacene interlayer for polymer bulk-heterojunction solar cell

We demonstrate that introducing a thin pentacene layer between metal cathode and photoactive layer results in a better than 50% improvement in the power conversion efficiency of polymer bulk-heterojunction solar cell when compared with the cell without the interlayer. An additional path for electron transfer provided by the thin pentacene layer appears to be mainly responsible for the improvement along with the increase in the open circuit voltage that occurs with increasing pentacene thickness. The concepts of utilizing additional charge transfer route and exploiting possible change in open circuit voltage with the inserted layer could widen avenues for enhancing the device performance. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2998583]