Functionalized hBN Quantum Dots as Optical Limiters in the Ultraviolet Region

Hexagonal boron nitride (hBN) quantum dots (QDs) have been synthesized using a top-down method. Pristine QDs exhibit wavelength-dependent emission spectra. The nonlinear optical (NLO) behavior of hBN QDs has been investigated for the first time using the self-diffraction geometry of the four-wave mixing technique and z-scan method. The optical properties are modified upon functionalization with suitable thiol (−SH) and aromatic amine (−NHR) ligands. It has been found that the spectroscopic and NLO responses are influenced by the transfer of charge carriers between the ligand and base hBN moiety. Functionalized QDs give rise to red-shifted emission and possess an enhanced NLO response. QDs show a promising optical limiting response, which makes them useful as a coating in protective eyewear for intense lasers.