Coal Pitch Derived Yellow-Emissive Carbon Dots and Their Application in Luminescent Solar Concentrators

Using coal pitch as the carbon source to synthesize carbon dots (CDs), one of the most promising photoluminescence (PL) materials, can play an important role in the global demand for carbon neutralization. However, the reported CDs derived from coal pitch are mainly limited blue emission. Here, a new route to synthesize yellow-emissive CDs from coal pitch is developed by extracting the lightweight aromatic compounds from coal pitch and solvothermally treating the extracts in dichloromethane in the presence of a small amount of nitric acid and sulfuric acid. Notably, the obtained CDs exhibit excitation independent yellow emission, large Stokes shift and good photostability. The application of the CDs for luminescent solar concentrators (LSCs) is evaluated. It is found that the CDs can be well dispersed in polymethyl methacrylate (PMMA) matrix and fabricated transparent LSCs. The synthesized LSC (4 × 4 × 0.2 cm³) with the optimal CDs concentration exhibits an optical conversion efficiency (η_opt) of 3.31% and power conversion efficiency (η_PCE) of 1.95% under simulated sun light illumination (100 mW cm⁻²). This research offers a new strategy to synthesize new kind of CDs with desired performance by exploiting the native chemistries of coal pitch.