Quantum-confined bandgap narrowing mechanism through which the absorption of two UV absorbers, namely the graphene quantum dots (GQDs) and TiO2 nanoparticles, can be easily extended into the visible light range in a controllable manner. Such a mechanism may be of great importance for light harvesting, photocatalysis and optoelectronics.
For the 1st time resesarchers have found a quantum-confined bandgap narrowing mechanism where UV absorption of the graphene quantum dots and TiO2 nanoparticles can easily be extended into the visible light range. Such a mechanism may allow the design of a new class of composite materials for light harvesting and optoelectronics. Dr Qin Li, A/Professor in the Environmental Engineering & Queensland Micro- and Nanotechnology Centre says real life application of this would be high efficiency paintable solar cells and water purification using sun light. “Wherever there is abundant sun we can brush on this nanomaterial to harvest solar energy to create clean water,” she says.
Visible light makes up 43% of solar energy compared to only 5% possessed by UV light. Major efforts have been made to improve titania’s absorption of visible light or develop visible-light sensitive materials in general. Methods used for titania, including metal ion doping, carbon doping, nitrogen doping and hydrogenation usually require stringent conditions to obtain the modified TiO2 such as elevated temperature or high pressure.
The researchers observed when TiO2 particles are mixed with graphene quantum dots, the resulting composite absorbs visible light by a quantum-confined bandgap narrowing mechanism.”We were really excited to discover this: when 2 UV absorbing materials, namely TiO2 and graphene quantum dots, were mixed together, they started to absorb in the visible range, more significantly, the bandgap can be tuned by the size of graphene quantum dots,” says Dr Li. “We named the phenomenon ‘quantum-confined bandgap narrowing’ and this mechanism may be applicable to all semiconductors, when they are linked with graphene quantum dots. Flexible tuning of bandgap is extremely desirable in semiconductor-based devices.”
https://app.secure.griffith.edu.au/news/2016/07/14/researchers-uncover-new-light-harvesting-potentials/
http://pubs.rsc.org/en/Content/ArticleLanding/2016/CC/C6CC03302D
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