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Cho DH, Park YS, Choi S, Cho H, Kwon BH, Shin JW, Cho NS. Luminance enhancement of top-emitting blue organic light emitting diodes encapsulated with silicon nitride thin films by a double-layer nano-structure. OPTICS EXPRESS 2022; 30:11959-11972. [PMID: 35473127 DOI: 10.1364/oe.452954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Even though it is in high demand to introduce a nano-structure (NS) light extraction technology on a silicon nitride to be used as a thin film encapsulation material for an organic light-emitting diode (OLED), only an industry-incompatible wet method has been reported. This work demonstrates a double-layer NS fabrication on the silicon nitride using a two-step organic vapor phase deposition (OVPD) of an industry-compatible dry process. The NS showed a wrinkle-like shape caused by coalescence of the nano-lenses. The NS integrated top-emitting OLED revealed 40 percent enhancement of current efficiency and improvement of the luminance distribution and color change according to viewing angle.
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Tae Lim J, Lee H, Cho H, Kwon BH, Sung Cho N, Kuk Lee B, Park J, Kim J, Han JH, Yang JH, Yu BG, Hwang CS, Chu Lim S, Lee JI. Flexion bonding transfer of multilayered graphene as a top electrode in transparent organic light-emitting diodes. Sci Rep 2015; 5:17748. [PMID: 26626439 PMCID: PMC4667220 DOI: 10.1038/srep17748] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/05/2015] [Indexed: 11/09/2022] Open
Abstract
Graphene has attracted considerable attention as a next-generation transparent conducting electrode, because of its high electrical conductivity and optical transparency. Various optoelectronic devices comprising graphene as a bottom electrode, such as organic light-emitting diodes (OLEDs), organic photovoltaics, quantum-dot LEDs, and light-emitting electrochemical cells, have recently been reported. However, performance of optoelectronic devices using graphene as top electrodes is limited, because the lamination process through which graphene is positioned as the top layer of these conventional OLEDs is a lack of control in the surface roughness, the gapless contact, and the flexion bonding between graphene and organic layer of the device. Here, a multilayered graphene (MLG) as a top electrode is successfully implanted, via dry bonding, onto the top organic layer of transparent OLED (TOLED) with flexion patterns. The performance of the TOLED with MLG electrode is comparable to that of a conventional TOLED with a semi-transparent thin-Ag top electrode, because the MLG electrode makes a contact with the TOLED with no residue. In addition, we successfully fabricate a large-size transparent segment panel using the developed MLG electrode. Therefore, we believe that the flexion bonding technology presented in this work is applicable to various optoelectronic devices.
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Affiliation(s)
- Jong Tae Lim
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Hyunkoo Lee
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Hyunsu Cho
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Byoung-Hwa Kwon
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Nam Sung Cho
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Bong Kuk Lee
- IT Convergence Technology Research Laboratory, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Jonghyurk Park
- Smart I/O Control Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Jaesu Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea
| | - Jun-Han Han
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Jong-Heon Yang
- Smart I/O Control Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Byoung-Gon Yu
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Chi-Sun Hwang
- Smart I/O Control Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
| | - Seong Chu Lim
- Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea.,IBS Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746, Korea
| | - Jeong-Ik Lee
- Soft I/O Interface Research Section, Electronics and Telecommunications Research Institute, Daejeon 305-700, Korea
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Park WY, Kwon Y, Lee C, Whang KW. Light outcoupling enhancement from top-emitting organic light-emitting diodes made on a nano-sized stochastic texture surface. OPTICS EXPRESS 2014; 22 Suppl 7:A1687-A1694. [PMID: 25607482 DOI: 10.1364/oe.22.0a1687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An effective method for enhancing the light outcoupling efficiency from top-emitting organic light-emitting diodes (TEOLEDs) with a nano-sized stochastic texture surface (NSTS) is suggested. The broadly distributed pitch and the randomly sized of islands in the NSTS enable the photons that are otherwise trapped to be emitted over the broad emission wavelength range. The NSTS-embedded TEOLEDs have wide angular-dependent emission characteristics and an enhanced external quantum efficiency (EQE). Theoretical and full-wave optical calculations were performed to understand the mechanisms of the efficiency enhancement. Optimized TEOLEDs achieved a 32% EQE enhancement compared with the reference devices without the NSTS.
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Kohl J, Pantina JA, O'Carroll DM. Enhancing surface plasmon leakage at the metal/semiconductor interface: towards increased light outcoupling efficiency in organic optoelectronics. OPTICS EXPRESS 2014; 22:7644-7656. [PMID: 24718140 DOI: 10.1364/oe.22.007644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The light outcoupling efficiency of organic light-emitting optoelectronic devices is severely limited by excitation of tightly bound surface plasmon polaritons at the metal electrodes. We present a theoretical study of an organic semiconductor-silver-SiO(2) waveguide and demonstrate that by simple tuning of metal film thickness and the emission regime of the organic semiconductor, a significant fraction of surface plasmon polariton mode amplitude is leaked into the active semiconductor layer, thereby decreasing the amount of optical energy trapped by the metal. At visible wavelengths, mode leakage increases by factors of up to 3.8 and 88 by tuning metal film thickness and by addition of gain, respectively.
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Schwab T, Fuchs C, Scholz R, Zakhidov A, Leo K, Gather MC. Coherent mode coupling in highly efficient top-emitting OLEDs on periodically corrugated substrates. OPTICS EXPRESS 2014; 22:7524-7537. [PMID: 24718126 DOI: 10.1364/oe.22.007524] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Bragg scattering at one-dimensional corrugated substrates allows to improve the light outcoupling from top-emitting organic light-emitting diodes (OLEDs). The OLEDs rely on a highly efficient phosphorescent pin stack and contain metal electrodes that introduce pronounced microcavity effects. A corrugated photoresist layer underneath the bottom electrode introduces light scattering. Compared to optically optimized reference OLEDs without the corrugated substrate, the corrugation increases light outcoupling efficiency but does not adversely affect the electrical properties of the devices. The external quantum efficiency (EQE) is increased from 15 % for an optimized planar layer structure to 17.5 % for a corrugated OLED with a grating period of 1.0 μm and a modulation depth of about 70 nm. Detailed analysis and optical modeling of the angular resolved emission spectra of the OLEDs provide evidence for Bragg scattering of waveguided and surface plasmon modes that are normally confined within the OLED stack into the air-cone. We observe constructive and destructive interference between these scattered modes and the radiative cavity mode. This interference is quantitatively described by a complex summation of Lorentz-like resonances.
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Fuchs C, Schwab T, Roch T, Eckardt S, Lasagni A, Hofmann S, Lüssem B, Müller-Meskamp L, Leo K, Gather MC, Scholz R. Quantitative allocation of Bragg scattering effects in highly efficient OLEDs fabricated on periodically corrugated substrates. OPTICS EXPRESS 2013; 21:16319-16330. [PMID: 23938484 DOI: 10.1364/oe.21.016319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bragg scattering effects in bottom-emitting organic light-emitting diodes (OLEDs) grown on corrugated aluminum-doped zinc oxide electrodes are analyzed. Periodic corrugation is introduced by structuring the oxide electrode via UV laser ablation, a process that enables flexible adjustment of the period and height of corrugation. We demonstrate that fabrication of stable and electrically efficient OLEDs on these rough substrates is feasible. Sharp spectral features are superimposed onto the broad emission spectra of the OLEDs, providing clear evidence for Bragg scattering of light from guided modes into the air cone. Theoretical analysis based on an emissive dipole model and conservation of momentum considerations allows a quantitative description of scattering and the associated dispersion relations.
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Affiliation(s)
- C Fuchs
- Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden,
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List EJW, Koch N. Focus Issue: Organic light-emitting diodes-status quo and current developments. OPTICS EXPRESS 2011; 19 Suppl 6:A1237-A1240. [PMID: 22109620 DOI: 10.1364/oe.19.0a1237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The guest editors introduce the Optics Express Energy Express supplement Focus Issue, "Organic Light-Emitting Diodes," which includes six invited articles addressing the challenges of light outcoupling and light management in OLEDs.
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Affiliation(s)
- Emil J W List
- NanoTecCenter Weiz Forschungsgesellschaft m.b.H., Franz-Pichler-Straße 32, A-8160 Weiz, Austria.
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