Rational design and fabrication of skeletal Cu7S4 nanocages for efficient counter electrode in quantum dot-sensitized solar cells. (March 2015) - Chen, Wenlong
Abstract: The widely used brass based Cu2 S counter electrodes (CEs) cannot stand the continuing corrosion in polysulfide electrolyte, which has limited the development of quantum dot-sensitized solar cells. Here, skeletal Cu7 S4 nanocages (SKE-Cu7 S4 ) with symmetric opening windows were rational designed and synthesized by kinetic roughening processes, and a possible formation mechanism had been proposed. Furthermore, SKE-Cu7 S4 onto fluorine-doped tin oxide glass substrates were designed and deposited to function as new efficient, stable and low cost CEs. Thanks to the 3D opening structure of SKE-Cu7 S4 CEs, the assembled QDSSCs exhibited a power conversion efficiency of 4.43% under 1 sun (100 mW cm −2 ) irradiation, while those of preformed 18 facet-Cu7 S4, Pt and brass/Cu2 S CEs are of 3.87%, 1.73% and 3.32%, respectively. Further studies by cyclic voltammetry measurements indicate the SKE-Cu7 S4 CEs still remain good cyclability after 600 cycles, demonstrating a super stable capability, while the commonly used brass/Cu2 S CEs show obvious fluctuation. Graphical abstract: Highlights: Skeletal Cu7 S4 nanocages with symmetric open windows were synthesized by a kinetic roughening process. The opening hollow structure can facilitate the diffusion of electrolyte and lead to a PCE of 4.43%. The SKE-Cu7 S4 CEs showed super long-term stable capability towards polysulfide electrolyte.