Visible light communication with efficient far-red/near-infrared polymer light-emitting diodes

Visible light communication(VLC)is a wireless technology that relies on optical intensity modulation and is potentially a game changer for internet-of-things(IoT)connectivity.However,VLC is hindered by the low penetration depth of visible light in non-transparent media.One solution is to extend operation into the“nearly(in)visible”near-infrared(NIR,700-1000 nm)region,thus also enabling VLC in photonic bio-applications,considering the biological tissue NIR semitransparency,while conveniently retaining vestigial red emission to help check the link operativity by simple eye inspection.Here,we report new far-red/NIR organic light-emitting diodes(OLEDs)with a 650-800 nm emission range and external quantum efficiencies among the highest reported in this spectral range(>2.7%,with maximum radiance and luminance of 3.5 mW/cm^(2) and 260 cd/m^(2),respectively).With these OLEDs,we then demonstrate a“real-time”VLC setup achieving a data rate of 2.2 Mb/s,which satisfies the requirements for IoT and biosensing applications.These are the highest rates ever reported for an online unequalised VLC link based on solution-processed OLEDs.