An efficient non-Lambertian organic light-emitting diode using imprinted submicron-size zinc oxide pillar arrays

Liu, S. W.; Wang, J. X.; Divayana, Yoga; Dev, Kapil; Tan, Swee Tiam; Demir, Hilmi Volkan; Sun, Xiao Wei

doi:10.1063/1.4791786

Cited by 21 publications

(17 citation statements)

References 22 publications

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“…Based on these results, and combined with its transparency over the visible region as well as the ability to be grown into a variety of nanostructures, it is hoped that the ZnO NRA can be further tailored to improve the out-coupling of light from the emissive organic layers [50][51][52] .…”

Section: Resultsmentioning

confidence: 99%

ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

Faria

Campbell

McLachlan

2015

Adv Funct Materials

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Nanostructured oxide arrays have received significant attention as charge injection and collection electrodes in numerous optoelectronic devices. Zinc oxide (ZnO) nanorods have received particular interest owing to the ease of fabrication using scalable, solution processes with a high degree of control of rod dimension and density. Here we implement vertical ZnO nanorods as electron injection layers in organic light emitting diodes (OLEDs) for display and lighting purposes. Implementing our nanorods into devices with an emissive polymer, poly(9,9-dioctyluorene-altbenzothiadiazole) (F8BT) and poly(9,9-di-n-octylfluorene-alt-N-(4-butylphenyl)dipheny-lamine) (TFB) as an electron blocking layer, brightness and efficiencies up to 8600 cd/m 2 and 1.66 cd/A were achieved. We highlight simple solution processing methodologies combined with post-deposition thermal processing to achieve complete wetting of the nanorod arrays with the emissive polymer. The introduction of TFB to minimize charge leakage and non-radiative exciton decay results in dramatic increases to device yields and provides an insight into the operating mechanism of these devices. We demonstrate the detected emission originates from within the polymer layers with no evidence of ZnO band-2 edge or defect emission. The work represents a significant development for the ongoing implementation of ZnO nanorod arrays into efficient light emitting devices.

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Section: Resultsmentioning

confidence: 99%

ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

Faria

Campbell

McLachlan

2015

Adv Funct Materials

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“…It has been previously demonstrated that photonic crystal nanostructures can be used above the glass surface for enhancing the LEE of an OLED device where the trapped light within the QLED escapes into the air as a result of Bragg diffraction and scattering from the nanostructures on the glass surface . Among them, ZnO nanostructures are promising materials as light outcoupling medium because of their high index and excellent optical transparency as well as easy solution fabrication process . For our case, the light extraction enhancement in QLEDs is investigated by placing ordered ZnO nanopillar arrays onto the glass surface of ITO‐glass substrates, as shown in Figure a.…”

Section: Resultsmentioning

confidence: 99%

Light Extraction Efficiency Enhancement of Colloidal Quantum Dot Light‐Emitting Diodes Using Large‐Scale Nanopillar Arrays

Yang

Dev

Wang

et al. 2014

Adv Funct Materials

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A colloidal quantum dot light-emitting diode (QLED) is reported with substantially enhanced light extraction effi ciency by applying a layer of largescale, low-cost, periodic nanopillar arrays. Zinc oxide nanopillars are grown on the glass surface of the substrate using a simple, effi cient method of non-wetting templates. With the layer of ZnO nanopillar array as an optical outcoupling medium, a record high current effi ciency (CE) of 26.6 cd/A is achieved for QLEDs. Consequently, the corresponding external quantum effi ciency (EQE) of 9.34% reaches the highest EQE value for green-emitting QLEDs. Also, the underlying physical mechanisms enabling the enhanced light-extraction are investigated, which leads to an excellent agreement of the numerical results based on the mode theory with the experimental measurements. This study is the fi rst account for QLEDs offering detailed insight into the light extraction effi ciency enhancement of QLED devices. The method demonstrated here is intended to be useful not only for opening up a ubiquitous strategy for designing high-performance QLEDs but also with respect to fundamental research on the light extraction in QLEDs.

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“…The ITO/ organic mode has been out-coupled by a hexagonalclose-packed array [5], and ultra-low-index grid [6]. Additionally, the substrate mode has been extracted using microlens arrays [7,8] and zinc oxide pillar arrays [9].…”

mentioning

confidence: 99%

Low-haze light extraction from organic light-emitting diode lighting with auxiliary electrode by selective microlens arrays

et al. 2013

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Improved out-coupling efficiency and low haze of organic light-emitting diode (OLED) lighting with an auxiliary electrode are demonstrated by selective microlens arrays (SMLAs). The microlens arrays, aligned with the auxiliary electrode, were selectively fabricated, since the fully packed microlens arrays lead to OLED lighting with high haze. The external quantum efficiency and power efficiency of the devices with the SMLAs increased by 32% when compared with the devices without these arrays. Using the SMLAs, dark grid lines in the emission region became brighter, with a low haze, and the spectra of the emitted light had no shift.

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An efficient non-Lambertian organic light-emitting diode using imprinted submicron-size zinc oxide pillar arrays

Cited by 21 publications

References 22 publications

ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

ZnO Nanorod Arrays as Electron Injection Layers for Efficient Organic Light Emitting Diodes

Light Extraction Efficiency Enhancement of Colloidal Quantum Dot Light‐Emitting Diodes Using Large‐Scale Nanopillar Arrays

Low-haze light extraction from organic light-emitting diode lighting with auxiliary electrode by selective microlens arrays

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