Photoluminescence mechanism of phosphorene quantum dots (PQDs) produced by pulsed laser ablation in liquids

Abstract

Phosphorene quantum dots (PQDs) with high photoluminescence (PL) quantum yield were fabricated through pulsed laser ablation of black phosphorus in liquids. The PL emission showed excitation wavelength-independent features due to the sufficient passivation by oxygen-containing substituents derived from the ablation-decomposed solvent molecules. There were four peaks in the PL profile showing a multifrequency PL effect, which provided a viable route to investigate the PL mechanism via the detailed structures of the PL profile. The two peaks at shorter wavelengths were attributed to the intrinsic PL transitions. The two peaks at longer wavelengths were assigned to the transitions from the lowest unoccupied molecular orbital to the two-surface states. The positions of the four peaks are redshifted with increasing solvent molecular chain length due to the passivation effect. The intense, excitation wavelength-independent, multifrequency and blue-violet PL emissions indicate the potential application in semiconductor light sources.