Near‐Infrared (NIR) Organic Light‐Emitting Diodes (OLEDs): Challenges and Opportunities

Zampetti, Andrea; Minotto, Alessandro; Cacialli, Franco

doi:10.1002/adfm.201905825

Cited by 78 publications

(106 citation statements)

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“…NIR-emitting devices are used in several different fields (please refer to ref. 26 for a more extensive review), including security, biodetection and photodynamic/photothermal therapy, with the latter two benefitting from the semitransparency of biological tissue in this spectral window. In the case of wearable or implanted biosensors, NIR photons can be used to both monitor human vital signs and wirelessly communicate with other devices.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Introductionmentioning

confidence: 99%

“…Achieving high fluorescence from OSs in the NIR is particularly hard because two major challenges must be overcome 26 . First, to obtain NIR emission, the energy gap of the chromophore must be reduced, thereby increasing the probability of non-radiative exciton decay (the socalled "energy-gap law") 27 .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Owing to the unique applications in the field of night‐vision technology, security recognition, optical telecommunication and photodynamic therapy, near‐infrared (NIR) emitting organic light‐emitting diodes (OLEDs) with emission peak beyond 700 nm have attracted increasing attention. To meet the requirements of these emerging applications, higher device efficiency is indispensable.…”

Section: Introductionmentioning

confidence: 99%

Boosting Efficiency of Near‐Infrared Organic Light‐Emitting Diodes with Os(II)‐Based Pyrazinyl Azolate Emitters

Yuan

Liao

et al. 2019

Adv Funct Materials

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Tremendous effort has been devoted to developing novel near-infrared (NIR) emitters and to improving the performance of NIR organic light-emitting diodes (OLEDs). Os(II) complexes are known to be an important class of NIR electroluminescent materials. However, the highest external quantum efficiency achieved so far for Os(II)-based NIR OLEDs with an emission peak wavelength exceeding 700 nm is still lower than 3%. A new series of Os(II) complexes (1-4) based on functional pyrazinyl azolate chelates and dimethyl(phenyl)phosphane ancillaries is presented. The reduced metal-to-ligand charge transfer (MLCT) transition energy gap of pyrazinyl units in the excited states results in efficient NIR emission for this class of metal complexes. Consequently, NIR OLEDs based on 1-4 show excellent device performance, among which complex 4 with a triazolate fragment gives superior performance with maximum external quantum efficiency of 11.5% at peak wavelength of 710 nm, which represent the best Os(II)-based NIR-emitting OLEDs with peak maxima exceeding 700 nm.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201906738. zation because of the strong spin-orbit coupling exerted by the thrid-row transition metal elements. [3,18,19] Among these, Pt(II)-based NIR OLEDs represent the state-of-the-art results in the range of 700-900 nm. [18,[20][21][22][23] In particular, in 2017, our group achieved a milestone in NIR OLEDs research, and realized NIR OLEDs with EQE up to 24 ± 1% at 740 nm by using the pyrazinyl pyrazolate Pt(II)-based emitter. [22] Although the efficiencies of these Pt(II)-based NIR OLEDs are remarkable, which also demonstrated a promising way to reduce the efficiency roll-off of the Pt(II)-based NIR OLEDs by using the metal-metal-to-ligand charge transfer (MMLCT) transition. [22][23][24] But in general, NIR OLEDs based on squareplanar Pt(II) emitters, particularly for porphyrin-based Pt(II) phosphors, typically suffer from serious efficiency roll-off at high current density, due to the long-lived triplet exciton generated and corresponding self-quenching. [18,21,25] In comparison Adv. Funct.

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“…Such low emission efficiencies are also a challenge for near‐infrared OLEDs . Efforts to improve both near‐infrared emission efficiency and charge transport in a single material have shown some success in recent years, but unfortunately high mobilities and current densities still very often also mean low EQE.…”

Section: Lateral Single Layer and Ambipolar Lefetsmentioning

confidence: 99%

Recent Developments and Novel Applications of Thin Film, Light‐Emitting Transistors

Zaumseil

2019

Adv Funct Materials

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Light-emitting field-effect transistors (LEFETs) combine switching and amplification with light emission and thus represent an interesting optoelectronic device. They are not limited anymore to a few examples and specific materials but are nearly universal for a wide range of semiconductors, from organic to inorganic and nanoscale. This review introduces the basic working principles of lateral unipolar and ambipolar LEFETs and discusses recent examples based on various solution-processed semiconducting materials. Applications beyond simple light emission are presented and possible future directions for lightemitting transistors with added functionalities are outlined. The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201905269.thus excluding vertical LEFETs, which have been demonstrated for some organic emitter systems. [5][6][7] We will start with LEFETs that do not rely on the injection of both holes and electrons in a single semiconducting layer but show unipolar charge transport and may include multiple semiconducting layers. This short section will be followed by an overview of truly ambipolar single-layer LEFETs, the different possible working principles and various emissive semiconductors with their advantages and drawbacks. The review will conclude with recent examples of LEFET applications that go beyond simple light-emission and take advantage of specific device properties to add functionalities that are difficult to achieve with other optoelectronic devices.

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Near‐Infrared (NIR) Organic Light‐Emitting Diodes (OLEDs): Challenges and Opportunities

Cited by 78 publications

References 0 publications

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

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

Boosting Efficiency of Near‐Infrared Organic Light‐Emitting Diodes with Os(II)‐Based Pyrazinyl Azolate Emitters

Recent Developments and Novel Applications of Thin Film, Light‐Emitting Transistors

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