We have fabricated large-area arrays of two dimensional cuboidal silver nanoparticles on ITO substrates with good control over the coverage density using the Langmuir Blodgett technique and integrated them in functional plasmonic devices with P3HT and PCBM as photoactive layer. The results demonstrate that for device structures with 13.5% surface coverage of cuboidal silver nanoparticles, IPCE and PCE increased by 20% and similar to 18% respectively. We attribute the improvements to enhanced absorption of the photoactive layer and an increase in exciton generation induced by strong local electric-field of the nanoparticles as well as an increased in the conductivity of the devices. (C) 2013 Elsevier B. V. All rights reserved.