Carbon nanotube network electrodes enabling efficient organic solar cells without a hole transport layer

We report on the effects of replacing both In2O3:Sn (ITO) and the hole transport layer (HTL) in organic photovoltaic (OPV) cells with single-walled carbon nanotube (SWNT) network transparent electrodes. We have produced an OPV device without an HTL exhibiting an NREL-certified efficiency of 2.65% and a short-circuit current density of 11.2 mA/cm(2). Our results demonstrate that SWNT networks can be used to replace both ITO and the HTL in efficient OPV devices and that the HTL serves distinctly different roles in ITO- and SWNT-based devices. (C) 2010 American Institute of Physics. [doi:10.1063/1.3453445]