Enhanced resonance energy transfer and white-light emission in carrot-derived carbon dots: utilizing complementary colors

Abstract

In this study, we explored resonance energy transfer (RET) between two carrot-derived carbon dots (S-CDs and P-CDs) and carrot extract (Crt), which eventually culminated in efficient white light emission (WLE). Herein, the carrot extract acted as an acceptor, while S-CDs and P-CDs both served as donors. The S-CDs and P-CDs were synthesized by the solvothermal treatment of the carrot extract with sulfuric acid and phosphoric acid, respectively. The synthesized CDs were characterized using high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), Fourier transmission infra-red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and fluorescence spectroscopy. Both S-CDs and P-CDs exhibited spherical morphologies with an average diameter of 2.8 and 3.1 nm, respectively. Remarkably, WLE was achieved in both solution and gel phases, the latter being formed using agar–agar. The Commission Internationale d’Eclairage (CIE) coordinates were (0.34, 0.32) in the solution phase, closely aligning with the pure white light coordinates (0.33, 0.33). The correlated colour temperature (CCT) for this mixture was 5041 K, indicating the cool nature of the generated white light. Interestingly, the CIE coordinates of (0.31, 0.35) realized in the gel medium also resemble very closely those of pure WLE. Detailed mechanistic investigations of resonance energy transfer (RET) were conducted using spectral overlap (J(λ)) and lifetime studies. The J(λ) values were 3.728 × 10⁹ M⁻¹ cm⁻¹ nm⁴ and 3.878 × 10⁸ M⁻¹ cm⁻¹ nm⁴ for pair I (S-CDs + Crt) and pair II (P-CDs + Crt), respectively, while Förster distances (R₀) were 0.79 nm and 0.54 nm for these pairs. To the best of our knowledge, this is the first report of WLE using two donors and one acceptor obtained from a plant extract and its derived carbon dots.