Opto-electrical properties of single layer flexible electroluminescence device with ruthenium complex

Santos, Gilmar Geraldo dos; Fonseca, Fernando Josepetti; Andrade, Adnei Melges de; Patrocínio, Antonio Otávio T.; Mizoguchi, S.K.; Iha, Neyde Yukie Murakami; Peres, M.; Simões, W.; Monteiro, T.; Pereira, L.

doi:10.1016/j.jnoncrysol.2007.10.064

Cited by 21 publications

(7 citation statements)

References 17 publications

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“…We note that Santos et al recently reported the first flexible SM-based LEC, but with a modest brightness level of 1 cd m À2 and a low power efficiency of 0.003 lm W À1 . [52] Thus, to the best of our knowledge, our finding represents the pioneering demonstration of a functional flexible LEC, which emits with high brightness and exhibits high power efficiency and a long operational lifetime.…”

Section: Introductionmentioning

confidence: 76%

The Design and Realization of Flexible, Long‐Lived Light‐Emitting Electrochemical Cells

Fang¹,

Matyba²,

Edman³

2009

Adv Funct Materials

123

120

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Polymer light‐emitting electrochemical cells (LECs) offer an attractive opportunity for low‐cost production of functional devices in flexible and large‐area configurations, but the critical drawback in comparison to competing light‐emission technologies is a limited operational lifetime. Here, it is demonstrated that it is possible to improve the lifetime by straightforward and motivated means from a typical value of a few hours to more than one month of uninterrupted operation at significant brightness (>100 cd m−2) and relatively high power conversion efficiency (2 lm W−1 for orange‐red emission). Specifically, by optimizing the composition of the active material and by employing an appropriate operational protocol, a desired doping structure is designed and detrimental chemical and electrochemical side reactions are identified and minimized. Moreover, the first functional flexible LEC with a similar promising device performance is demonstrated.

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Section: Introductionmentioning

confidence: 76%

The Design and Realization of Flexible, Long‐Lived Light‐Emitting Electrochemical Cells

Fang¹,

Matyba²,

Edman³

2009

Adv Funct Materials

123

120

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“…In 2008, Santos et al reported the first milestone with the first LEC capable of maintaining light emission while in a deformed state. [48] This work used a composite of the iTMC complex [Ru(bpy) 3 ](PF 6 ) 2 dispersed in poly(methyl methacrylate) (PMMA) as the emissive material, which had been previously implemented in rigid LECs using a transparent anode of ITO on glass by Lee et al [27] Santos et al created the flexible analogue by depositing the emissive composite on a flexible ITO/PET anode, with an aluminum film deposited by PVD as the cathode. The brightness of a few cd m −2 and efficiency (0.0024 cd A −1 ) of these devices, however, were lower than those of the analogous devices fabricated using an ITO/glass TCE (200-500 cd m −2 ), which the authors attributed to the high electrical resistance of the ITO/PET substrate (R s = 1000 Ω sq −1 ) and inhomogeneity of the spin-coated iTMCpolymer emissive layer.…”

Section: Flexible Lecs Using An Ito/pet Tcementioning

confidence: 99%

25 Years of Light‐Emitting Electrochemical Cells: A Flexible and Stretchable Perspective

et al. 2021

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advantages and disadvantages. OLEDs are tunnel diode devices that require the work function of the electrode materials to be matched to the HOMO-LUMO energies of the emissive material, and require reactive metals with low work functions to achieve efficient electron injection directly into the emissive polymer. [3] In contrast, the applied voltage in a LEC device initially causes the movement of the ions in the emissive layer, creating ohmic contacts that facilitate charge injection regardless of the electrode work function. [4] This unique operating mechanism enables the convenience of air-stable electrodes that can be chosen regardless of the HOMO-LUMO energies of the emissive material, and bipolar operation with a rectification ratio near unity. Because of the ohmic contacts, the operating voltage of LECs is, in principle, comparable to the HOMO-LUMO bandgap energy. The devices are more tolerant than OLEDs to the thickness and roughness of emissive layer, which can range from nanometer to micrometer scale. Despite these advantages, over the past 25 years it is the OLED that has emerged as a formidable market force in commercial lighting, ultimately becoming a pinnacle of display technology. With a well-understood operating mechanism in hand, an extensive academic research and industrial R&D community tackled the problem of the low external quantum efficiencies (EQEs) and high driving voltages of early OLEDs from a variety of different angles. These efforts increased the complexity of the device architecture by adding functional material layers to balance charge injection and transport for optimized emissive recombination (Figure 1a). The first OLED television, the Sony XEL-1, became commercially available in 2008. [5] The development of LECs, in contrast, took a very different path. Instead of increasing complexity to improve device performance, the field initially remained mired in developing an understanding of the complexities of the device operating mechanism, eventually reaching a unified operating model in 2010 that combined the sometimes contradictory electrochemical and electrodynamic operating models initially proposed. [6] As OLEDs and LECs went their separate ways, the LEC largely remained in the realm of academic research and retained the simple architecture of its inception (Figure 1b), emerging as a robust and fault-tolerant platform-a sandbox-for researchers to explore new emissive materials, electrode materials, fabrication strategies, and device operating conditions. Light-emitting electrochemical cells (LECs) are simple electroluminescent devices comprising an emissive material containing mobile ions sandwiched between two electrodes. The operating mechanism of the LEC involves both ionic and electronic transport, distinguishing it from its more well-known cousin, the organic light-emitting diode (OLED). While OLEDs have become a leading player in commercial displays, LECs have flourished in academic research due to the simple device architecture and unique features of its operating mechanism...

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“…Nevertheless, there is still ongoing research for a higher color purity and internal efficiency associated with a very high emission intensity (approximately 1000 cd/m 2 ) from more sophisticated organic materials. Rare earth and transition metal complexes are suitable candidates, especially those based on europium, terbium, rhenium and ruthenium [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Oxygen Plasma Surface Treatment onto ITO Surface for OLEDs Based on Europium Complex

Santos¹,

Cavallari²,

Fonseca³

et al. 2020

JICS

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In this work, Organic Light-Emitting Diodes (OLEDs) based on Europium (III) complex were studied, especially those with an oxygen plasma surface treatment onto indium tin oxide (ITO) transparent electrode. An OLED with the same thin-film structure but with untreated ITO was fabricated for comparison purposes. Current density-voltage characteristics for treated devices demonstrated an increase from 0.4 to 3.3 mA/cm² and a decrease of the turn-on voltage from 28 to 22 V. Additionally, improved hole injection through the transparent electrode impacted on optical response, as luminous efficiency increased from 26 to 44 mcd/A with the advantage of no significant disturb on the europium typical electroluminescence emission spectrum. Emission peak was observed at a wavelength of approximately 614 nm, which is defined by the transition associated with spectroscopic terms (5D0→7D2) and CIE chromaticity coordinates of (0.50;0.36).

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Opto-electrical properties of single layer flexible electroluminescence device with ruthenium complex

Cited by 21 publications

References 17 publications

The Design and Realization of Flexible, Long‐Lived Light‐Emitting Electrochemical Cells

The Design and Realization of Flexible, Long‐Lived Light‐Emitting Electrochemical Cells

25 Years of Light‐Emitting Electrochemical Cells: A Flexible and Stretchable Perspective

Oxygen Plasma Surface Treatment onto ITO Surface for OLEDs Based on Europium Complex

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