Design and fabrication of carbon dots decorated WO3 nanosheets hybrid photoanodes for sunlight-driven dye-sensitized solar cell applications

This work demonstrates the selection of the substrates to be used for photoanode and counter electrode for dye-sensitized solar cells (DSSC). A novel carbon dots (CDs) decorated WO₃ nanosheets hybrid structure was synthesized by facile hydrothermal route, which acts as a photoanode materials: counter electrode (Pt) and iodide/triiodide (I⁻/I₃⁻). Sun stimulator (AM 1.5G, 100 mW/cm²) is used as source of light to evaluate the photovoltaic characteristics. The samples using various mass ratios (1:1, 1:2, 1:3) of CDs and WO₃ were prepared under the same conditions. The monoclinic structure with sheet-like morphology of WO₃ was identified by XRD, Raman and TEM measurements. The optimized CDs/WO₃ (1:3) photoanode exhibits a huge surface area (102.4 m²/g) and porous size (12 nm) since the CDs are rapidly anchored on the WO₃ nanosheets. Due to the high absorption ability that prevents the recombination rate of the electron–hole pair, the optimized CDs/WO₃ (1:3) photoanode delivers a high photoconversion efficiency of 11.7%, which is 3.35 times better than that of bare WO₃ (3.5%). The improved photoconversion efficiency of WO₃ by carbon was also discussed in detail.