We fabricated a plasmonic layer by immobilizing both Au and Ag nanoparticles via P4VP on a photoactive layer for dye-sensitized solar cells (DSSCs) to prevent aggregation of metal nanoparticles, to increase absorbance of N719 dye, and to enhance light harvesting and power conversion efficiency (PCE). The optimal conditions for immobilizing these nanoparticles were also examined. With plasmonic Au and Ag nanoparticles, the PCE increased by 8.05% and 5.78%, respectively (plasmonic Au nanoparticles: from 8.82% to 9.53%; plasmonic Ag nanoparticles: from 8.82% to 9.33%). When both Au and Ag nanoparticles were employed in the plasmonic layer, the PCE showed further improvement of 10.17%, corresponding to a 15.31% enhancement. This significant improvement of the PCE could be explained by a broader range of light absorption resulting from the presence of the plasmonic layer. (C) 2017 Elsevier B.V. All rights reserved.