Ca/Ag bilayer cathode for transparent white organic light-emitting devices

Lee, C.J.; Pode, Ramchandra; Han, Jeong In; Moon, Dae‐Gyu

doi:10.1016/j.apsusc.2006.09.026

Cited by 22 publications

(6 citation statements)

References 21 publications

(23 reference statements)

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“…It has been reported by Lee in 2007 that the presence of Ca(OH) 2 in the Ca/Ag structure cathode can improve the optical transparency. [12] This is in agreement with what we have found that the transmittance of bilayer semitransparent is slightly higher than that of single silver layer.…”

Section: B Hole Injection Layersupporting

confidence: 92%

P‐109: Efficient p‐i‐n Top‐emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil

Kao

et al. 2009

Symp Digest of Tech Papers

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A high‐efficiency p‐i‐n top‐emitting flexible organic light emitting diode (TFOLED) employing highly reflective Ag as anode and semitransparent Ca/Ag as cathode was fabricated on SS substrate which was insulated and planarized with a specially formulated photoresist coating. By incorporating p‐dopant (WO3) and a new n‐dopant (PAK2) in hole and electron transparent layers, respectively, along with an optimized microcavity structure, a green fluorescent C545T doped Alq3 TOLED on SS substrate achieved one of the highest efficiencies of 26.7 cd/A and 19.8 lm/Wat 20 mA/cm2 reported for flexible OLEDs.

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Section: B Hole Injection Layersupporting

confidence: 92%

P‐109: Efficient p‐i‐n Top‐emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil

Kao

et al. 2009

Symp Digest of Tech Papers

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“…The reasons we believed are as follows. The light extraction for the OLEDs with the Ce (11 nm)/Au (15 nm) cathode and a p-Si anode is still lower than that of conventional devices by a factor of 3-5 due to the limited transmittance of the cathode, the low reflectance and the considerable absorption of the p-Si anode; the holes injection from the Fig.1 The transmittance spectra for Ce (4,9,11 nm)/Au (15 nm) cathodes in the range from 400 to 600 nm; Inset: Power dissipation spectrum at 520 nm for the TOELDs with the Ce (11 nm)/Au (15 nm) and an Al (11 nm)/Au (15 nm) cathode p-Si anode is enhanced compared to ITO [9] , so a better carrier balance should be rebuilt. There are some other unknown factors, such as the interface of the Si/NPB interface, still restricting the efficiency.…”

Section: Resultsmentioning

confidence: 98%

“…Our device structures are p-Si/SiO 2 /NPB (60 nm)/Alq (60 nm)/Ce (4,9,11,13,16 nm)/Au (15 nm). An indium tin oxide (ITO) anode device with Ce (11 nm)/Au (15 nm) cathode was also fabricated for comparison.…”

Section: Methodsmentioning

confidence: 99%

“…The transparent cathodes are required to possess high transparency, high electron injection ability, and high stability. Up to now, Transparent cathodes such as ultrathin Mg:Ag [7,8] , Ca/Ag double layer [9,10] , and dielectric/metal stacked layer [11][12][13][14][15] have been reported, and very recently some top emission schemes have achieved device performances competitive with bottom emission ones [16][17][18][19][20][21][22] . In this article, we present an alternative semitransparent Ce/Au cathode and demonstrate an efficient TOLED with p-type Si anode.…”

Section: Introductionmentioning

confidence: 99%

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Organic light emitting diodes with p-Si anodes and semitransparent Ce/Au cathodes

Sun

Guang-zhi

2011

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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The Ce (x nm)/Au (15 nm) stacked layers were used as semitransparent cathodes in the top-emission organic light emitting devices (TOLEDs) fabricated on a p-type silicon anodes and substrate, where x varies from 4 to 16. The consequence of the Ce layer thickness on transmittance and the device performance were studied when the organic layers NPB (60 nm)/ALQ (60 nm) were kept unchanged, where NPB was N, N'-bis-(1-naphthl)-diphenyl-1, 1'-biphenyl-4, 4'-diamine, and AlQ is tris-(8-hydroxyquinoline) aluminum. The cathode of Ce (11 nm)/Au (15 nm) has a transparency of 46%, and the TOLED with it achieves the highest luminescence efficiencies: a current efficiency of 0.91 cd/A at 13.7 V and a peak power efficiency of 0.28 lm/W at 9 V. The turn-on voltage is 3.0 V. The Ce/Au cathode is both chemically and electrically stable.

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“…The binding energy of the Ca-O bond was higher than that of Ca-Ca one, which agrees well with previously reported results. 33,34 The Ca 2p 3/2 spectrum had the full width half maximum value of about 2.49 eV and it did not change with the increase of Ca thickness. The ratio of Ca-O/ Ca-Ca was calculated to be 0.91.…”

Section: Chemical Composition Analysis Of the Ca/ag Double Layer Usin...mentioning

confidence: 97%

Modulation of surface plasmons coupling for enhancement of optical transmittance of silver-coated alkaline-earth metal films

et al. 2012

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We enhanced the optical transmittance of silver-coated alkaline-earth metal films by modulation of surface plasmons (SPs) coupling. The result indicates that the optical transmittance of a metal film is controlled by the SPs coupling at the interface of the metal with a dielectric substrate. Because the SPs originate from the coupling between the free charge at the surface of the metal and the incident light, there exists the SPs coupling in an Ag layer with the dielectric substrate. These SPs lead to longitudinal surface charge density fluctuations that propagate along the substrate/Ag interface, resulting in the decreased transmittance property (47.9% in the visible region) of the 10 nm thick Ag layer on the dielectric substrate. Because both alkaline-earth metal and Ag have negative dielectric constants, the incident light cannot induce the SPs in the alkaline-earth metal/Ag double layer. Thus, inserting a thin alkaline-earth metal layer between Ag and the dielectric substrate could modulate the SPs coupling at the Ag/substrate interface and, hence, the optical transmittance of alkaline-earth metal/Ag films. Both alkaline-earth metal and Ag could be formed by thermal evaporation and in situ synchrotron radiation photoelectron spectroscopy results showed that the thermally evaporated alkaline-earth metal (Ca) film is composed of metallic (Ca) and metal-oxide (CaO) components. It is found that the SPs modulation optimized alkaline-earth metal/Ag (10 nm/10 nm) film has obtained a higher optical transmittance (69.8%) in the visible region than that of an Ag layer. This led to the enhanced maximum luminance of organic light emitting diodes with the alkaline-earth metal/Ag electrode from 24 300 cd m À2 to 32 700 cd m À2 .

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Ca/Ag bilayer cathode for transparent white organic light-emitting devices

Cited by 22 publications

References 21 publications

P‐109: Efficient p‐i‐n Top‐emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil

P‐109: Efficient p‐i‐n Top‐emitting Flexible Organic Light Emitting Diodes on Planarized Stainless Steel Foil

Organic light emitting diodes with p-Si anodes and semitransparent Ce/Au cathodes

Modulation of surface plasmons coupling for enhancement of optical transmittance of silver-coated alkaline-earth metal films

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