The electrical properties of polymer solar cells (PSCs) with gold nanoparticles (AuNPs) embedded in the hole transport layers (Hits) were investigated. The PSCs with AuNP-embedded HTLs exhibited 8%, 9.5%, and 22% enhancement in short-circuit current density, open-circuit voltage, and power conversion efficiency, respectively. The low contact resistance at the active layer/Hit interface resulted in the high collection efficiency and low electron-hole recombination. The downshift of the Fermi energy in AuNP-embedded HTLs lowered the energy barrier and thinned the depletion layer at the active layer/HTL interface, accounting for the enhanced collection efficiency. (C) 2013 Elsevier B.V. All rights reserved.