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Friday, 21 Jul 2017

Researchers at NTU and NTHU achieve high-efficiency near IR OLED at 740nm

Bright and efficient organic emitters of near-infrared light would be of use in applications ranging from biological imaging and medical therapy to night-vision devices

16 Dec 2016 | Editor

Researcher teams from the National Taiwan University (NTU) and National Tsing Hua University (NTHU) have announced they have synthesised a platinum complex compound that can form a linear array able to extend efficient light-emitting wavelengths to the near infrared (IR) spectrum (740nm).

According to news reports this achievement advances the "world record" of the efficiency of near IR OLED and is considered a "breakthrough" in an emission energy as previously OLED materials used emitted little or no light when their light-emitting energy gap moved close to the near IR end of the spectrum and as well as experiencing a large decay of light from exciton-phonon coupling.

The platinum complex developed results in a large reduction in the impact of exciton-phonon coupling, and consequently allowing efficient light emission at the near IR spectrum.

NTU and NTHU - IR OLED devices and performance data

Figure: NTU and NTHU - a, J–V–R characteristics. b, EQE and PCE as a function of brightness. c, Maximum radiance with and without a hemisphere light out-coupling structure. d, Operation of the ∼740 nm OLED using Pt(II) complex 1.

Near IR OLEDs are important because they hold the potential to be suitable in a wide range of applications - such as:

  • vehicle proximity sensors
  • medical applications - as near IR light can penetrate organic tissues such as skin
  • night-vision devices

Near-infrared organic light-emitting diodes with very high external quantum efficiency and radiance

Kiet Tuong Ly | Ren-Wu Chen-Cheng | Hao-Wu Lin | Yu-Jeng Shiau | Shih-Hung Liu | Pi-Tai Chou | Cheng-Si Tsao | Yu-Ching Huang | Yun Chi

Nature Photonics (2016) | doi:10.1038/nphoton.2016.230

Received 30 June 2016 | Accepted 17 October 2016 | Published online 28 November 2016

Abstract

Bright and efficient organic emitters of near-infrared light would be of use in applications ranging from biological imaging and medical therapy to night-vision devices. Here we report how a new class of Pt(II) complex phosphors have enabled the fabrication of organic light-emitting diodes that emit light at 740 nm with very high efficiency and radiance due to a high photoluminescence quantum yield of ∼81% and a highly preferred horizontal dipole orientation. The best devices exhibited an external quantum efficiency of 24 ± 1% in a normal planar organic light-emitting diode structure. The incorporation of a light out-coupling hemisphere structure further boosts the external quantum efficiency up to 55 ± 3%.

www.digitimes.com    www.nthu.edu.tw    www.ntu.edu.tw   

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