Bright Stretchable Alternating Current Electroluminescent Displays Based on High Permittivity Composites

Stauffer, Flurin; Tybrandt, Klas

doi:10.1002/adma.201602083

Cited by 126 publications

(146 citation statements)

References 28 publications

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“…To control the electric field distribution around the emitting centers, which is governed by the dielectric properties of the emission layer, Tybrandt and co‐workers developed a high permittivity stretchable electroluminescent composite . The finer BaTiO 3 particles were incorporated into the larger ZnS: Cu particles layer in a two‐step process ( Figure a), which enhanced the loading of ZnS: Cu particles up to 54 vol%.…”

Section: Optimizing Strategies For Ac‐driven El Devicesmentioning

confidence: 99%

Advances in Alternating Current Electroluminescent Devices

Wang

Lian

et al. 2019

Advanced Optical Materials

106

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radiatively at the active emissive layer driven by constant-voltage or direct current (DC). However, the DC-driven mode for OLEDs and QLEDs limits their practical applications. One reason is that the unidirectional DC flow may lead to unfavorable charges accumulation at high current density. Furthermore, the power losses are unavoidable as the DC-driven devices require power converters and rectifiers when connected to the 110/220 V at 50/60 Hz alternating current (AC) power sources. OLEDs are also particularly sensitive to dimensional variations accompanied by the generation of leakage currents at such imperfections, which is unfavorable for their application in flexible electronics. Consequently, AC-driven EL devices have attracted attention as promising alternatives to DC-driven EL devices for a variety of applications. [25][26][27][28][29][30][31][32][33] AC-driven EL devices are primarily composed of electrodes, an emissive layer and a single-or multilayer of insulating dielectric without the critical requirement for energy band matching, which facilitates their application in large-scale displays and flexible devices. [34] The device structure of AC-driven EL devices can be mainly divided into three kinds: i) AC-driven thin film electroluminescent (AC-TFEL) devices; ii) AC-driven lightemitting devices (AC-LEDs), and iii) AC-driven light-emitting field effect diodes (AC-LEFETs). Under the AC electric field, light generation is based on either the hot-electron impact excitation mechanism or the exciton recombination mechanism, depending on the device configuration. Despite the different operation principles, AC-driven EL devices have shown specific Alternating current (AC)-driven electroluminescent (EL) devices have recently attracted attention as potential alternatives to direct current (DC)-driven organic light-emitting diodes (OLEDs), as they have the great advantage of easy integration into the AC power system of 110/220 V at 50/60 Hz without complicated back-end electronics. However, the high driving voltage and low power efficiency inherent to AC-driven EL devices limit their widespread application. While researchers have made some remarkable progress in this field, the underlying causes during the development process remain to be explored. The strategies for improving the performance of AC-driven EL devices with different configurations, such as the conventional sandwiched structure and multilayer-based light-emitting devices, are summarized in this review. For example, it is crucial to enhance the effective electric field around the emitters for AC-driven thin film electroluminescent (AC-TFEL) devices, while the unbalanced generation/injection of charge carriers is the main limiting factor for the performance of AC-driven light-emitting devices (AC-LEDs). The recent advances in AC-driven EL devices, with some new configurations or new-type emitting materials, are presented by category. The challenges and opportunities for the further development of AC-driven EL devices are also discussed.

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Section: Optimizing Strategies For Ac‐driven El Devicesmentioning

confidence: 99%

Advances in Alternating Current Electroluminescent Devices

Wang

Lian

et al. 2019

Advanced Optical Materials

106

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“…In recent years, enormous attention and research enthusiasm have been devoted to high dielectric (high-k) materials for their wide applications in actuators [1,2], antennas [3], capacitors [4][5][6][7], wave-transparent (or absorbing) devices [8][9][10][11][12][13], and other electronic devices [14][15][16][17][18][19][20][21][22]. Most conventional highk materials are ceramic or ceramic composites, but their applications are seriously restricted by their intrinsic frangibility, high density, poor plasticity, and low breakdown strength.…”

Section: Introductionmentioning

confidence: 99%

Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

Mao

Shi

Wang

et al. 2018

Adv Compos Hybrid Mater

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The search for high-performance dielectric materials has long been driven by the urgent needs for various modern electronics. However, enhanced permittivity is always accompanied by elevated loss, which seriously hinders the development and applications of dielectric materials. Herein, negative-k layers were introduced into layer-structured films, forming a new class of multilayer composites consisting of alternately stacked positive-k and negative-k layers. Compared with traditional multilayer composites without negative-k layers, the layered composites containing extra positive-k/negative-k interfaces exhibit superior ability in balancing the contradict parameters: permittivity and loss, yielding substantially enhanced permittivity without sacrificing the low loss. It is indicated that the permittivity was enhanced by the charge accumulations and reinforced polarizations on the interfaces between positive-k and negative-k layers. Meanwhile, the loss induced by the leakage current was suppressed by the blocked transport of carriers between adjacent layers. The trilayered 60-3.5-60 composite exhibits an enhanced dielectric constant (ε′ ≈ 33 @10 kHz) and retained low loss (tanδ ≈ 0.12 @10 kHz) compared with the single-layer BT/PVA composite containing 60 wt% BT fillers (ε′ ≈ 9.5 @10 kHz, tanδ ≈ 0.075 @10 kHz). This research offers an effective way to design and fabricate novel high-performance dielectric materials.

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“…Moreover, ZnS‐based EL devices generally exhibit great strain endurance and mechanical robustness when subjected to crude mechanical manipulations such as bending, twisting, and stretching . Third, silicone was selected to act as the dielectric layer to prevent the breakdown of the device, and to function as the binder of ZnS particles . Furthermore, the silicone was utilized to encapsulate the ACEL fibers.…”

Section: Resultsmentioning

confidence: 99%

Coaxial‐Structured Weavable and Wearable Electroluminescent Fibers

Liang

et al. 2017

Adv Elect Materials

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Flexible, lightweight, and wearable devices are currently attracting tremendous interest in the field of advanced electronics. In this work, novel 1D, flexible, coaxial-structured, bright and colorful alternating current electroluminescent (ACEL) fibers consisting of AgNW-based electrodes, a ZnS phosphor layer, and silicone dielectric and encapsulation layers are designed and fabricated through a simple protocol. This facile all-solution-based fabrication protocol enables scalable production of long ACEL fibers (>12 cm). Stemming from the rational design and facile fabrication process, the as-prepared ACEL fibers exhibit uniform, bright, and angularly independent luminance (up to 202 cd m −2 @ 195 V and 2 kHz). Benefiting mainly from the robust AgNWbased electrodes and versatile silicone, the ACEL fibers exhibit additionally excellent flexibility and mechanical stability, being capable to maintain ≈91% of luminance after 500 bending-recovery cycles, as well as mitigated luminance degradation after continuous work in ambient. The proper length combined with superb mechanical properties makes the ACEL fibers readily weavable. Most notably, the isolating, hydrophobic, and biocompatible silicone encapsulation layer endows the ACEL fibers unprecedented wearability. Eventually, a proof-of-concept ACEL fabric is demonstrated by weaving the asprepared long ACEL fibers, to show the future perspective of directly weaving ACEL fibers into densely arrayed wearable functional cloths. Flexible Electronics

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Bright Stretchable Alternating Current Electroluminescent Displays Based on High Permittivity Composites

Cited by 126 publications

References 28 publications

Advances in Alternating Current Electroluminescent Devices

Advances in Alternating Current Electroluminescent Devices

Improved dielectric permittivity and retained low loss in layer-structured films via controlling interfaces

Coaxial‐Structured Weavable and Wearable Electroluminescent Fibers

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