Oxygen-vacancy and depth-dependent violet double-peak photoluminescence from ultrathin cuboid SnO_2 nanocrystals

摘要

A double peak in the violet region between 360 and 400 nm is observed from the photoluminescence spectra acquired from cuboid SnO_2 nanocrystals and the energy separation between the two subpeaks increases with nanocrystal size. The phenomenon arises from band edge recombination caused by different in-depth distributions of oxygen vacancies (OVs). Density functional theory calculations disclose that variations in the oxygen vacancies with depth introduce valence-band peak splitting leading to the observed splitting and shift of the double peak.