Nontoxic blue-emitting hexagonal BN quantum dots for QLED application synthesized by solvothermal pyrolysis of ammonia borane

Hexagonal boron nitride (h-BN) quantum dots (QDs), as a member of van der Waals family, also know as white graphene, have attracted increasing attention due to their unique properties in terms of metal-free, nontoxic, and earth-abundant source. However, the large-scale synthesis of high-quality h-BN QDs is still a challenge. In this work, we for the first report the synthesis of blue-emitting h-BN QDs via pyrolysis of ammonia borane in CCl4 solvent. The as-synthesized h-BN QDs have super-high crystallinity and uniform size distribution (3–7 nm). A prototype device of QLED using the h-BN QDs as the emitting layer was demonstrated. The peak wavelength of the electroluminescence of the QLED device, located at 412 nm, is longer than that of photoluminescence peaked at 386 nm. The intrinsic band gap of the h-BN QDs is determined to be 5.05 eV. Therefore, the luminescence mechanism is considered with crystal defects of trapped unpaired electrons in the 3-B centers.