A Facile Route to Efficient, Low‐Cost Flexible Organic Light‐Emitting Diodes: Utilizing the High Refractive Index and Built‐In Scattering Properties of Industrial‐Grade PEN Substrates

Kim, Eunhye; Cho, Hyunsu; K, Kim; Koh, Tae‐Wook; Chung, Jaiho; Lee, Jonghee; Park, YongKeun; Yoo, Seunghyup

doi:10.1002/adma.201404862

Cited by 109 publications

(71 citation statements)

References 43 publications

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“…However, WOLEDs with high luminous efficacy (LE) overcoming LEDs at high luminance are believed to be a distant goal at present even with large advances in light extraction during the last couple of decades . Those advances include scatter, low refractive index layer, micro lens array, photonic crystal, low/high refractive index grid, high refractive index substrate, corrugated structure, graded index, randomly distributed pillar array, biomimetic structure, plasmonic nanocavity, and so on. Among the proposed methods, the insertion of extraction medium between the glass and the indium tin oxide (ITO) electrode is regarded to have potential for further efficiency enhancement by extracting the waveguide mode in combination with the extraction method at the glass–air interface.…”

Section: Performance Of Woleds II W/o and W/ Vanha And Half‐sphericalmentioning

confidence: 99%

High‐Quality White OLEDs with Comparable Efficiencies to LEDs

Jeon

Lee

Han

et al. 2018

Advanced Optical Materials

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high luminous efficacy (LE) overcoming LEDs at high luminance are believed to be a distant goal at present even with large advances in light extraction during the last couple of decades. Those advances include scatter, [1][2][3][4][5][6][7][8][9] low refractive index layer, [10] micro lens array, [11][12][13][14] photonic crystal, [15][16][17][18] low/high refractive index grid, [19][20][21] high refractive index substrate, [9,22,23,27] corrugated structure, [24][25][26][27][28][29][30][31][32] graded index, [33] randomly distributed pillar array, [34,35] biomimetic structure, [36,37] plasmonic nanocavity, [38] and so on. Among the proposed methods, the insertion of extraction medium between the glass and the indium tin oxide (ITO) electrode is regarded to have potential for further efficiency enhancement by extracting the waveguide mode in combination with the extraction method at the glass-air interface. However, despite the efficiency improvement due to the extraction layer, many of these methods often have limitations such as diffraction pattern and color distortion to be applied to general illumination systems and high-performance electronic devices. [15][16][17][18][24][25][26][27][28][29][30][31] To solve these problems such as the angular dependence and diffraction pattern, a random pattern is introduced, but the currently reported random patterns are obtained by using spontaneous methods which have difficulty in quantitative control of randomness and poor reproducibility. [34,35] It would also be recommended that the internal extraction structure does not distort the planar structure in OLEDs to prevent the potential degradation issue coming from the rough structure because active layers of OLEDs are very thin.Here, we report novel WOLEDs approaching the theoretical limit by using the highly effective extraction layer based on a randomly dispersed vacuum nanohole array (VaNHA). The random VaNHA pattern was designed with random number generation function in the unit cell of 10 × 10 µm 2 to show no specific symmetry in the reciprocal space. The random VaNHA WOLEDs in combination with a half-spherical lens exhibited comparable performance with LED lighting with unprecedentedly high LE of 164 lm W −1 , originating from high maximum external quantum efficiency (EQE) of 78% and low efficiency roll-off. In addition, the WOLEDs showed uniform emission of high-quality light with high correlated color temperature (CCT) of 3400 K, high color rendering index (CRI) around 80, no color variation with viewing angle. The light extraction structure does not have any additional detrimental effect on the device The solid-state lighting sources require high efficiency and high-quality illumination at the same time. Here, highly efficient white organic light emitting diodes (WOLEDs) comparable to LEDs are demonstrated using a random vacuum nanohole array and a half-spherical lens as internal and external light extraction layers, respectively, exhibiting the maximum external quantum efficiency of 78% and luminous efficacy of...

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Section: Performance Of Woleds II W/o and W/ Vanha And Half‐sphericalmentioning

confidence: 99%

High‐Quality White OLEDs with Comparable Efficiencies to LEDs

Jeon

Lee

Han

et al. 2018

Advanced Optical Materials

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“…To further enhance the light extraction or light trapping in the devices, nanostructures or nanoparticles are introduced into these TFC electrodes for improving the device performances [47,[130][131][132][133][134][135][136][137][138][139][140]. Besides these thin-film electrodes, fiber-/mesh-shaped electrodes also demonstrated good flexibility [17,51,64,67,68].…”

Section: Design Of Flexible Electrodesmentioning

confidence: 99%

“…The reported electrodes utilized in flexible OLEDs are mainly based on PEDOT [173], CNT [44,174], Ag NWs/grids [175][176][177][178][179], graphene [45,180], ITO [76], and metal oxide [181]. For achieving higher efficiency, top-emitting architectures [182][183][184][185] and nanostructured/scattered electrodes or substrates [47,[130][131][132][133][134][135] can be adopted, to enhance output coupling or light extraction of the devices. However, to achieve high flexibility, extremely bendable TFC electrodes firstly need to be developed [88,120,124,146,147,177,186].…”

Section: Ultraflexible Oledsmentioning

confidence: 99%

Thin-film organic semiconductor devices: from flexibility to ultraflexibility

Qian

Zhang

et al. 2016

Sci. China Mater.

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Flexible thin-film organic semiconductor devices have received wide attention due to favorable properties such as light-weight, flexibility, reproducible semiconductor resources, easy tuning of functional properties via molecular tailoring, and low cost large-area solution-procession. Among them, ultraflexible electronics, usually with minimum bending radius of less than 1 mm, are essential for the development of epidermal and bio-implanted electronics, wearable electronics, collapsible and portable electronics, three dimensional (3D) surface compliable electronics, and bionics. This review firstly gives a brief introduction of development from flexible to ultraflexible organic semiconductor electronics, and design of ultraflexible devices, then summarizes the recent advances in ultraflexible thin-film organic semiconductor devices, focusing on organic field effect transistors, organic light-emitting diodes, organic solar cells and organic memory devices.

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“…In this regard, high refractive index (HRI) materials (RI > 1.50), with the capability to increase refraction and decrease the reflection, play an important role on the overall performance of many opto‐electronic devices . Due to their intrinsic ability to widen the critical angle, HRI materials can be widely applied as encapsulating materials to increase external quantum efficiency in organic light emitting diode (OLED) devices, and to enhance conversion efficiency in solar cells devices . Furthermore, they can be used in many other areas, such as coating materials of microlenses, antireflection films in spectacles, waveguides, and organic lasers …”

Section: Introductionmentioning

confidence: 99%

High Refractive Index Hyperbranched Polymers Prepared by Two Naphthalene-Bearing Monomers via Thiol-Yne Reaction

Wei

Zan

Qiu

et al. 2016

Macromol. Chem. Phys.

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High refractive index (HRI) materials play an important role in optic‐electronic devices. In this study, two compounds with high content of naphthalene groups, 1,5‐dithiolnaphthalene and 1,3,5‐tris(naphthalyl–ethylnyl) benzene, are selected as “A2” and “B3” monomers, respectively to prepare hyperbranched HRI polymers. Metal‐free radical‐initiated “A2 + B3” thiol‐yne polyaddition is conducted successfully at different monomer molar ratios even for those sterically demanding molecules being able to adjust the molar mass as well as RI. Polymers with refractive index up to 1.79 at 589.7 nm are obtained, which are among the highest RI values so far reported for pure polymer‐based materials. The high RI, based on the high molar refraction of naphthalene group, metal‐free and easy one‐pot synthesis, high transparency in the visible area, good thermal stability, good solubility, and easy processability into thin films, make these polymers excellent candidates for optic‐electronic applications.

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A Facile Route to Efficient, Low‐Cost Flexible Organic Light‐Emitting Diodes: Utilizing the High Refractive Index and Built‐In Scattering Properties of Industrial‐Grade PEN Substrates

Cited by 109 publications

References 43 publications

High‐Quality White OLEDs with Comparable Efficiencies to LEDs

High‐Quality White OLEDs with Comparable Efficiencies to LEDs

Thin-film organic semiconductor devices: from flexibility to ultraflexibility

High Refractive Index Hyperbranched Polymers Prepared by Two Naphthalene-Bearing Monomers via Thiol-Yne Reaction

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