Quantification of energy loss mechanisms in organic light-emitting diodes

Meerheim, Rico; Furno, Mauro; Hofmann, Simone; Lüssem, Björn; Leo, Karl

doi:10.1063/1.3527936

Cited by 316 publications

(255 citation statements)

References 10 publications

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“…The air mode exhibits two maxima at approximately 80 and 260 nm within the examined thickness range. This result is very similar to the results of previous calculations and simulations [12,14]. As shown in Fig.…”

Section: ～10supporting

confidence: 82%

Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

Jeong¹,

Ko²

2013

Journal of the Optical Society of Korea

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The effect of diffusing substrate and pillow lenses on the outcoupling efficiency of organic light-emitting diodes (OLEDs) was studied by optical simulation based on the point-dipole model. The diffusing substrate included Mie scatterers by which the condition of total internal reflection could be broken. The finite-difference time-domain method was used to obtain the intensity distribution on the transparent electrode of an OLED, which was used as a light source to carry out a ray-tracing simulation of the OLED and the diffusing substrate. It was found that the outcoupling efficiency of the OLED was sensitive to the thickness of organic layers and could be increased by 21.0% by adopting a diffusing substrate in which Mie scatterers whose radius was 2.0 μm were included at the density of 10 7 mm -3 and by 65.5% by forming one pillow lens with the radius of 2 mm on the front surface of the glass substrate. This study revealed that the outcoupling efficiency could be improved by adopting diffusing substrate and pillow lenses along with the optimization of the thickness of each layer in the OLED.

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Section: ～10supporting

confidence: 82%

Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

Jeong¹,

Ko²

2013

Journal of the Optical Society of Korea

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“…optical wave guide (WG) modes, losses from absorption, and excitations of surface plasmon polariton (SPP) modes at metal interfaces. 18 Either the OLED suffers from large losses due to the SPP mode, which is excited at the metallic opaque back reflector, or, if the distance between organic emitter and the metal is increased, another WG mode as source of loss is introduced, while the SPP excitation is strongly reduced. 18 Typically, even though the experimentalist is free to ponder between different types of loss channels, known OLED layouts cannot exceed the limit mentioned above.…”

Section: 3-5mentioning

confidence: 99%

Enhanced light emission from top-emitting organic light-emitting diodes by optimizing surface plasmon polariton losses

et al. 2015

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We demonstrate enhanced light extraction for monochrome top-emitting organic light-emitting diodes (OLEDs). The enhancement by a factor of 1.2 compared to a reference sample is caused by the use of a hole transport layer (HTL) material possessing a low refractive index (∼ 1.52). The low refractive index reduces the in-plane wave vector of the surface plasmon polariton (SPP) excited at the interface between the bottom opaque metallic electrode (anode) and the HTL. The shift of the SPP dispersion relation decreases the power dissipated into lost evanescent excitations and thus increases the outcoupling efficiency, although the SPP remains constant in intensity. The proposed method is suitable for emitter materials owning isotropic orientation of the transition dipole moments as well as anisotropic, preferentially horizontal orientation, resulting in comparable enhancement factors. Furthermore, for sufficiently low refractive indices of the HTL material, the SPP can be modeled as a propagating plane wave within other organic materials in the optical microcavity. Thus, by applying further extraction methods, such as micro lenses or Bragg gratings, it would become feasible to obtain even higher enhancements of the light extraction.

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“…This enhances light outcoupling to some extent, even though it does not completely solve the problem of TIR. [10][11][12] Thomschke et al 13 demonstrated the lamination of a high refractive index microlens foil on top of a white OLED and obtained a device efficacy of over 30 lm/W (27% EQE). Recently, Kim et al achieved an EQE of 44.7% (1.8-fold enhancement) for a green top-emitting OLED using a microlens array that was fabricated by evaporating an organic capping layer through a shadow mask.…”

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confidence: 99%

White top-emitting organic light-emitting diodes with solution-processed nano-particle scattering layers

Schaefer

Schwab

Lenk

et al. 2015

Applied Physics Letters

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A random scattering approach to enhance light extraction in white top-emitting organic light-emitting diodes (OLEDs) is reported. Through solution processing from fluorinated solvents, a nano-particle scattering layer (NPSL) can be deposited directly on top of small molecule OLEDs without affecting their electrical performance. The scattering length for light inside the NPSL is determined from transmission measurements and found to be in agreement with Mie scattering theory. Furthermore, the dependence of the light outcoupling enhancement on electron transport layer thickness is studied. Depending on the electron transport layer thickness, the NPSL enhances the external quantum efficiency of the investigated white OLEDs by between 1.5 and 2.3-fold. For a device structure that has been optimized prior to application of the NPSL, the maximum external quantum efficiency is improved from 4.7% to 7.4% (1.6-fold improvement). In addition, the scattering layer strongly reduces the undesired shift in emission color with viewing angle.

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Quantification of energy loss mechanisms in organic light-emitting diodes

Cited by 316 publications

References 10 publications

Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

Enhanced light emission from top-emitting organic light-emitting diodes by optimizing surface plasmon polariton losses

White top-emitting organic light-emitting diodes with solution-processed nano-particle scattering layers

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