In-situ fabrication of N-doped carbon dots on novel blue-emitting Y2TiWO8: Ce3+ nanophosphor for thermal sensing and fingerprint detection applications

A series of N-doped Carbon Dots @ Ce3+-doped Y2TiWO8 blue-emitting nanophosphors were obtained by the sol-gel assisted hydrothermal route for exploring the optical thermometry and latent fingerprint visualisation. X-Ray Diffraction, morphology, and PL spectra analysed the synthesised nanophosphors. Excited by 355 nm, the Ce3+-doped Y2TiWO8 nanophosphor shows a broad blue emission band at 424 nm, resulting from the electric dipole transition 5d → 4f of Ce3+ and the N-doped Carbon Dots @ Ce3+-doped Y2TiWO8 nanophosphor shows the blue emission band at 431 nm. A dramatic increase by a factor of 342.82 was observed in PL intensity when nitrogen doped carbon dots were embedded in the Ce3+-doped Y2TiWO8 nanophosphor. The enhanced PL intensity can be attributed to the FRET mechanism. Compared to its emission intensity at room temperature, the nanophosphor maintains 85 % of its intensity even at 400 K, demonstrating outstanding thermal stability. The N-doped Carbon Dots@ Ce3+-doped Y2TiWO8 exhibit high colour purity of 93.25 %. Further, the nanophosphor can be potentially used for optical thermometry with a wide temperature range from 300 K to 460 K. The latent fingerprint developed by N-doped Carbon Dots@ Ce3+-doped Y2TiWO8 nanophosphor presents excellent selectivity and high contrast. Under UV irradiation, latent fingerprints' level 1–3 structural features may be easily recognised.