Emission
from Trions in Carbon Quantum Dots
- Publication date
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Abstract
The photoluminescence (PL) spectra
acquired from 1 to 6 nm large
carbon quantum dots (CQDs) prepared by refluxing activated carbon
in HNO<sub>3</sub> show blue emission independent of the excitation
wavelength as well as long-wavelength emission depending on the excitation
wavelength. The dependence of the two emissions on pH is investigated,
and the experimental results show that the peak position of the long-wavelength
emission does not change with pH; however, the blue emission becomes
more asymmetrical, and obvious shoulder peaks emerge as the pH increases.
A model based on defect-bound trions in the CQDs is proposed to explain
the shoulder peaks in the blue emission at high pH, and the calculated
results agree well with experimental data concerning the integral
intensity ratio of the trion to exciton emissions versus pH. Our experimental
and theoretical results demonstrate for the first time emission from
trions in CQDs