Improved performance of mixed single layer top-emission organic light emitting devices using capping layer

Wang, Zhao-Kui; Naka, Shigeki; Okada, Hiroyuki

doi:10.1016/j.sse.2010.11.007

Cited by 9 publications

(4 citation statements)

References 33 publications

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“…Consequently, an additional MoO 3 capping layer was introduced to clad the Ag cathode to improve light extraction [ 50 , 51 ]. MoO 3 has a high refractive index and a low extinction coefficient [ 52 , 53 ]. By thermally depositing a 30 nm MoO 3 capping layer, the transmittance of Ag film could be increased ( Figure S3 ).…”

Section: Resultsmentioning

confidence: 99%

Top-Emitting Active-Matrix Quantum Dot Light-Emitting Diode Array with Optical Microcavity for Micro QLED Display

Lai

Yang²,

Tsai³

et al. 2022

Nanomaterials

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An electroluminescent quantum-dot light-emitting diode (QLED) device and a micro QLED device array with a top-emitting structure were demonstrated in this study. The QLED device was fabricated in the normal structure of [ITO/Ag/ITO anode]/PEDOT:PSS/PVK/QDs/[ZnO nanoparticles]/Ag/MoO3, in which the semi-transparent MoO3-capped Ag cathode and the reflective ITO/metal/ITO (IMI) anode were designed to form an optical microcavity. Compared with conventional bottom-emitting QLED, the microcavity-based top-emitting QLED possessed enhanced optical properties, e.g., ~500% luminance, ~300% current efficiency, and a narrower bandwidth. A 1.49 inch micro QLED panel with 86,400 top-emitting QLED devices in two different sizes (17 × 78 μm2 and 74 × 40.5 μm2) on a low-temperature polysilicon (LTPS) backplane was also fabricated, demonstrating the top-emitting QLED with microcavity as a promising structure in future micro display applications.

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Section: Resultsmentioning

confidence: 99%

Top-Emitting Active-Matrix Quantum Dot Light-Emitting Diode Array with Optical Microcavity for Micro QLED Display

Lai

Yang²,

Tsai³

et al. 2022

Nanomaterials

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“…As the thickness of MoO x of devices E, F, and B increases, the performance first improved and then decreased. Since MoO x acted as a matching layer to integrate the light radiated by AgNPs, [ 42 ] the excessive refraction length of the thick film resulted in the loss of the light radiation. The performance of device F was the best among all the devices, with the maximum CE, EQE, and luminance of 28.27 cd A −1 , 13.09%, and 34 247 cd m −2 , respectively.…”

Section: Resultsmentioning

confidence: 99%

Enhancing the Light Output‐Coupling of Inverted Top‐Emitting Organic Light‐Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles

Zhao

Niu

Shi

et al. 2022

Adv Materials Inter

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maximum (FWHM) and current efficiency (CE) of the TEOLEDs are significantly optimized owing to the micro-cavity effect of the top-emitting structure, promoting the applications in ultra-high-definition displays and micro-displays. [11,12] However, one major challenge of the TEOLEDs is the severe waveguide and plasmonic losses, which hinders the light outputcoupling and results in the low external quantum efficiency (EQE). [13,14] Introducing the localized surface plasmon resonance (LSPR) in the device is an effective way to increase the EQE of the OLEDs. [15,16] The LSPR is generated by overlapping the local electromagnetic field of excitons in the emitting layer and the surface plasmons of the noble metal in form of the nanowire and nanoparticles (NPs). [17][18][19][20][21] When the absorption peak of the metal NPs matches the emission wavelength of the device, the local electromagnetic fields around the NPs at a specific wavelength are enhanced. [22,23] More importantly, the LSPR is greatly influenced by the size of the noble metal NPs. [24,25] By precisely adjusting the size and the spacing of the NPs, the resonance wavelength of the NPs can be tuned to well match the wavelength of the electroluminescence (EL) spectra of OLEDs. [26,27] However, there are few reports on the effect of the LSPR on the inverted TEOLEDs.In this study, we have introduced a light output-coupling layer (LOCL) composed of AgNPs and MoO x on the top capping layer (CPL) of the inverted TEOLED device. The AgNPs in the LOCL could significantly improve the light output-coupling of the TEOLED owing to the LSPR, and the MoO x in the LOCL could effectively protect the water-and oxygen-sensitive electron injection material. In addition, the FWHM is narrowed to 50 nm due to the micro-cavity effect of the top-emitting structure and the turn-on voltage (V on , calculated at the lowest brightness of ≈1 cd m −2 ) is decreased to 2.6 V with Ag 2 O doped 4,7-diphenyl-1,10-phenanthroline (Bphen) as electron injection layer (EIL). Through systematical analysis and the finite difference time domain simulation (FDTD), we found that when the thickness of the AgNPs was 0.5 nm and the thickness of MoO x was 20 nm, the light output-coupling of the device reached the best. The CE and the EQE were increased 1.53 and 1.3 times to 28.3 cd A −1 and 13.11%, and the luminance achieves 34 247 cd m −2 .In this study, a light out-coupling layer (LOCL) composed of Ag nanoparticles (NPs) and MoO x is introduced on top of the inverted top-emitting organic light-emitting diode (OLED). The full width at half maximum (FWHM) is narrowed to 50 nm due to the micro-cavity effect of the top-emitting structure and the turn-on voltage is as low as 2.6 V. The AgNPs in the LOCL significantly improves the light output-coupling of the OLED owing to the localized surface plasmon resonance, and the MoO x in the LOCL effectively protects the water-and oxygen-sensitive electron injection material. As a result, the performance of the OLED with the LOCL is significantly enhanced. The maximum...

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“…On these backgrounds, our research group has been studying various kinds of organic electronic devices. For the purpose of a simple device process, good long-term stability with identical device characteristics, we have studied the OLEDs with a mixed single-layer (MSL), [26][27][28][29][30][31][32][33][34][35][36][37] application to a special solution-processed OLED, 29,[38][39][40][41][42][43] using inkjet printing technology, [44][45][46][47][48][49][50] and the OLED fabricated with spray method. 51,52) In order to express multi-functional abilities of the organic materials, we have studied a doublefaced emission panel with different images, named a "Dual-Drive Emission (DDE) panel", 53,54) an organic light-sensing device 55,56) and X-ray sensing devices, 57) a stacked device structure of OLED and light-sensing devices, named "Bifunction Matrix Array (Bi-Matrix)", 58,59) multi-function devices with single organic device structure, [60][61][62][63][64][65] and an organic-scanner with the OLED as a light source.…”

Section: Introductionmentioning

confidence: 99%

Mixed single-layer and self-alignment technology of organic light-emitting diodes and multi-functional integration in organic devices

Okada¹,

Naka²

2020

Jpn. J. Appl. Phys.

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Mixed-single layer and self-alignment technology of organic light-emitting diodes and multi-functional integration in organic devices have been reviewed. For the fabrication of solution-processed organic light-emitting diodes, the structure of the mixed-single layer is simple and the selection of small organic molecules is superior than that of polymer organic material because many researchers are actively studying the chemical synthesis. From an aspect in the application of the organic devices, multi-functional abilities of an emission, a sensing and an integration are necessary. In this paper, we have collected up reported devices and concepts in the field of organic electronics.

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Improved performance of mixed single layer top-emission organic light emitting devices using capping layer

Cited by 9 publications

References 33 publications

Top-Emitting Active-Matrix Quantum Dot Light-Emitting Diode Array with Optical Microcavity for Micro QLED Display

Top-Emitting Active-Matrix Quantum Dot Light-Emitting Diode Array with Optical Microcavity for Micro QLED Display

Enhancing the Light Output‐Coupling of Inverted Top‐Emitting Organic Light‐Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles

Mixed single-layer and self-alignment technology of organic light-emitting diodes and multi-functional integration in organic devices

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