  Graphene and related two-dimensional materials are promising candidates for
atomically thin, flexible, and transparent optoelectronics. In particular, the
strong light-matter interaction in graphene has allowed for the development of
state-of-the-art photodetectors, optical modulators, and plasmonic devices. In
addition, electrically biased graphene on SiO2 substrates can be used as a
low-efficiency emitter in the mid-infrared range. However, emission in the
visible range has remained elusive. Here we report the observation of bright
visible-light emission from electrically biased suspended graphenes. In these
devices, heat transport is greatly minimised; thus hot electrons (~ 2800 K)
become spatially localised at the centre of graphene layer, resulting in a
1000-fold enhancement in the thermal radiation efficiency. Moreover, strong
optical interference between the suspended graphene and substrate can be
utilized to tune the emission spectrum. We also demonstrate the scalability of
this technique by realizing arrays of chemical-vapour-deposited graphene bright
visible-light emitters. These results pave the way towards the realisation of
commercially viable large-scale, atomically-thin, flexible and transparent
light emitters and displays with low-operation voltage, and graphene-based,
on-chip ultrafast optical communications.
