Abstract:

High-fluorescence intensity silicon/nitrogen co-doped carbon dots （Si/N-CDs） are successfully synthesized by photochemical catalysis， using N-phenyl p-phenylenediamine and 3-aminopropyl trimethoxysilane as the raw materials. The properties of Si/N-CDs are characterized by transmission electron microscopy （TEM）， X-ray photoelectron spectroscopy （XPS）， fluorescence spectroscopy， X-ray diffraction （XRD）， and infrared spectroscopy （FT-IR）， respectively. Si/N-CDs have a spherical shape with an average diameter of 6.45 nm， a bright blue-green fluorescence under 365 nm UV illumination， as well as a quantum yield of 30.8%. The Si/N-CDs are continuously tested for 30 days and 5 h of continuous ultraviolet radiation. In this study， Si/N-CDs are used to replace the blue and green rare earth phosphor in the red/green/blue trichromatic rare earth phosphor， and the white light-emitting diode （WLED） is prepared by compounding with a red phosphor （Sr，Ca） AlSiN₃∶Eu²⁺ composite. Running the WLED at 60 mA current， a high color rendering index of 86.9 and a luminescence efficiency of 7.76 lm/W can be achieved. The color coordinates of the WLED are （0.3773， 0.3734）， the color temperature is 4062 K， and the color points located on the blackbody Planck trajectory， indicating that the prepared WLED can produce high-quality illumination effects. The silicon and nitrogen co-doped carbon dots have facile preparation method and excellent optical properties， which can replace blue/green rare earth phosphors to prepare high-quality lighting WLED with red light-emitting phosphors， expanding the application of carbon dots in light-emitting devices. Meanwhile， Si/N-CDs have low toxicity， stable optical properties and simple synthesis process， making it of potential commercial application prospects in the replacement of blue/green rare earth phosphors.

Key words: Silicon and nitrogen co-doped carbon dots, Photochemical synthesis, Optical properties, Light-emitting diodes