Hole transit in P3HT:PCBM solar cells with embedded gold nanoparticles

• Polymer solar cells with AuNP-embedded HTLs exhibit enhancement in Jsc, Voc, and PCE.
• Embedment of AuNPs results in the downshift of the Fermi energy of HTLs.
• Low contact resistance at active layer/HTL interfaces accounts for the high collection efficiency.

The electrical properties of polymer solar cells (PSCs) with gold nanoparticles (AuNPs) embedded in the hole transport layers (HTLs) 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/HTL 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.