Quantum Confinement Effect in the Absorption Spectra of Graphene Quantum Dots

Our preliminary investigation of the absorption and the photoluminescence response of selectively separated graphene quantum dots using centrifugation indicate that the photoluminescence is more sensitive to the size of the quantum dot than the absorption. We observed similar to 143nm blueshift from 623nm to 480nm in the visible region of the photoluminescence with increasing successive centrifugation (decreasing size) and not in the corresponding absorption spectra in the visible region. However, for the first time, we observed a blueshift in the absorption spectra in the UV regions that is tentatively attributed to quantum confinement. Further detailed work is underway to confirm the blueshift in the absorption and correlate with deep UV photoluminescence and morphological quantification of the quantum dots size distribution using high resolution transmission electron microscope.