ACS Nano http://doi.org/m5v (2013)

Researchers have demonstrated that graphene can improve the performance of a broad range of devices thanks to its unique optical, chemical, thermal and mechanical characteristics. Now, Seungae Lee and co-workers take advantage of all these properties simultaneously and demonstrate that graphene can also be suitable as an encapsulating material. The authors disperse graphene sheets at a low concentration in a silicone resin and use this blend to cover inorganic white light-emitting diodes. The brightness of this light source is not impaired by the graphene nanosheets, because of their high optical transmittance; rather, the device benefits from the blend cover, which shows an improved thermal conductivity, a lower thermal expansion coefficient, and reduced permeability to moisture and hydrogen sulphide gas. The enhanced protection from external agents and faster heat dissipation increase the long-term stability of the diode: indeed its luminous flux remains almost unchanged over 1,000 h of continuous operation.