A low-cost lithographic technique to pattern poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) films with 10 nm deep features of 700 nm periodicity is demonstrated. The use of these patterned films in poly (3-hexylthiophene) : [6,6]-phenylC(61)-butyric acid methyl ester organic photovoltaic devices leads to an increase in short circuit current (J(sc)), fill factor, and power conversion efficiency (PCE) with only a slight reduction in open circuit voltage. Patterning the PEDOT: PSS at 150 degrees C increases Jsc from 2.44 to 3.03 mA/cm(2) improving the PCE from 0.63% to 0.81% with similar increases due to patterning also being obtained at other temperatures.