Hydrophilicity and polarity of cubic silicon carbide nanocrystals identified from photoluminescence emissions in various solvents

Abstract

Since the surface-structure-related state dominates the photoluminescence (PL) emissions of cubic silicon carbide (3C-SiC) nanocrystals (NCs) with a diameter lower than 3.0 nm, the PL lines of 3C-SiC NCs in deionized water with different pH values, methanol, ethanol, chloroform, and toluene are characterized at the excitation of 300 to 360 nm. The position and intensity of the PL peaks provide experimental evidence that the surface of 3C-SiC is hydrophilic and hydroxyl bonding on the surface decreases the energy gap of the NCs. The PL emission wavelength of 3C-SiC NCs can be adjusted by adjusting the pH value of the solvent. The polar 3C-SiC NCs prefer to precipitate in chloroform and toluene.