Influence of Plasmonic Au@Cl/N Co-doped Carbon Dots on the Performance of Dye-Sensitized Solar Cells

Abstract

The synergistic influence of the LSPR (localized surface plasmon resonance) of gold nanoparticles (Au NPs) and the effect of nitrogen and chlorine co-doped carbon dots (Cl/N-CQDs) on dye-sensitized solar cells (DSSCs) performance are investigated. The gold NPs are coated with a thin layer of Cl/N-CQDs to produce the Au@Cl/N-CQDs structure. DSSCs are fabricated by using Au@Cl/N-CQDs as co-sensitizer. The focus of this work is to examine the effects of plasmonic Au NPs and carbon dots in addition to their synergistic effect by capping the Au NPs with Cl/N-CQDs, and track their influence in DSSCs. N719 as ruthenium-based dye, and natural dyes including betanin, crocin, carthamin, curcumin, chlorophyll, mallow, and lawsone are selected and applied in the DSSCs co-sensitized by Au@Cl/N-CQDs. The power conversion efficiency (PCE) of DSSCs using all of the selected dyes is enhanced upon using the Au@Cl/N-CQDs. It is due to the improvement in VOC (open circuit voltage) and JSC (short circuit photocurrent densities) relative to the use of dyes alone. Based on computational results, Au@Cl/N-CQDs cause a red-shift in comparison with pure dyes. The TD-DFT (time-dependent density functional theory) results show that the orbitals from the Au@Cl/N-CQDs in dye/Au@Cl/N-CQDs have contribution in most of the absorptions. In other words, electrons from HOMO (highest occupied molecular orbital) of Au@Cl/N-CQDs is transferred to the LUMO (lowest unoccupied molecular orbital) of dye, in most cases.