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

Abstract

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.

Non-toxic near-infrared light-emitting diodes

“…For the small-molecule-doped PLEDs, the effective strategy requires optimization of the doping concentration to reach the best compromise between the opposite needs of suppressing concentration-caused emission quenching and exciton annihilation and of ensuring efficient energy transfer from the host to quench its luminescence and afford purely NIR emission. Very recently, we demonstrated new far-red/ NIR LEDs with a 650 to 800 nm emission range by incorporating a fluorescent p-expanded diketopyrrolopyrrole dye (eDPP) blended in an F8BT polymer matrix (Minotto et al, 2020). In this case, an optimal dopant (Zampetti et al, 2017;Minotto et al, 2020).…”

“…Very recently, we demonstrated new far-red/ NIR LEDs with a 650 to 800 nm emission range by incorporating a fluorescent p-expanded diketopyrrolopyrrole dye (eDPP) blended in an F8BT polymer matrix (Minotto et al, 2020). In this case, an optimal dopant (Zampetti et al, 2017;Minotto et al, 2020). (C) Molecular structures of the PIDT-TPD/PIDT-2TPD host polymers and BTT* NIR dye (Minotto et al, 2018).…”

Ultrathin, Ultra‐Conformable, and Free‐Standing Tattooable Organic Light‐Emitting Diodes

“…[ 12,13 ] The reduction of OLED thickness [ 14 ] is usually the most obvious strategy to increase device flexibility and conformability. In addition, OLEDs can offer connectivity via visible light communication [ 15,16 ] and thus enable implementation of the internet‐of‐thing. At present, there is a lack of displays/communication devices offering the properties necessary to enable ultra‐flexible [ 17 ] and ultra‐conformable devices, [ 18 ] whereas the development of a versatile ultrathin and ultra‐conformable OLED would boost a variety of novel potential applications.…”

EVM Loss: A Loss Function for Training Neural Networks in Communication Systems

“…In general, LEDs are low bandwidth devices and as the demand for data is ever-increasing, methods to improve spectral efficiency are currently in high demand. Candidates to do this in VLC have either been through equalization [ 2 ], or through advanced modulation schemes [ 3 ]. Of the latter, of the most promising is spectrally efficient frequency division multiplexing (SEFDM), a modification of orthogonal frequency division multiplexing (OFDM) first proposed in 2006 by Rodrigues and Darwazeh in [ 4 ].…”