Graphene-based nanohybrid materials as the counter electrode for highly efficient quantum-dot-sensitized solar cells

Abstract

Dry plasma reduction is an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic AuPt nanoparticles (NPs) on a graphene nanoplatelets (GC)-coated layer under atmospheric pressure at a low temperature and without using any toxic reductants. The NPs with an average size of about 2nm were stably and uniformly hybridized on the surface of reduced graphene nanoplatelets (RGC) after co-reduction of metal precursor ions and GC to metal atoms and RGC, respectively. Quantum-dot-sensitized solar cells exploiting AuNP/RGC, PtNP/RGC and bimetallic AuPtNP/RGC counter electrodes (CEs) exhibited power conversion efficiencies of 2.7%, 3.0% and 4.5%, respectively. The efficiencies are comparable to that of device with a conventional Au-sputtered CE (3.6%). The effect is ascribed to high electrochemical catalytic activity and high electrical conductivity of developed nanohybrid materials.