CuInS<sub>2</sub>‐Based Quantum Dot Light‐Emitting Electrochemical Cells (QLECs)

Frohleiks, Julia; Wefers, Fabian; Wepfer, Svenja; Hong, A-Ra; Jang, Ho Seong; Nannen, Ekaterina

doi:10.1002/admt.201700154

Cited by 26 publications

(16 citation statements)

References 60 publications

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“…These promising properties ensure their potential application in low‐cost displays. Among the reported emissive materials used in LECs, for example, polymers, ionic transition metal complexes (iTMCs), small molecules, and quantum dots/nanoparticles, phosphorescent iTMCs usually exhibit the higher electroluminescence (EL) efficiency. Therefore, tremendous effort has been made to improve the device performance of iTMC‐based LECs …”

Section: Introductionmentioning

confidence: 99%

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Lin

Liu

et al. 2019

Chemistry A European J

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Solid‐state light‐emitting electrochemical cells (LECs) have several advantages, such as low‐voltage operation, compatibility with inert metal electrodes, large‐area flexible substrates, and simple solution‐processable device architectures. However, most of the studies on saturated red LECs show low or moderate device efficiencies (external quantum efficiency (EQE) <3.3 %). In this work, we demonstrate a series of five red‐emitting cationic iridium complexes (RED1‐‐RED5) with 2,2′‐biquinoline ligands and test their electroluminescence (EL) characteristics in LECs. The Commission Internationale de l′Eclairage (CIE) 1931 coordinates for the LECs based on these complexes are all beyond the National Television System Committee (NTSC) red standard point (0.67, 0.33). The maximal EQE of the neat‐film RED1‐based LECs reaches 7.4 %. The reddest complex, RED3, is doped in the blue‐emitting host complex, BG, to fabricate host–guest LECs. The maximal EQE of the host–guest LECs (1 wt % complex RED3) reaches 9.4 %, which is among the highest reported for the saturated red LECs.

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Section: Introductionmentioning

confidence: 99%

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Lin

Liu

et al. 2019

Chemistry A European J

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“…Light‐emitting electrochemical cells (LECs) are attractive electroluminescent (EL) devices for potential flat‐panel display and lighting applications due to their simple, solid‐state construction and compatibility with low‐cost fabrication processes . Compared to organic light‐emitting diodes (OLEDs), LECs exhibit a much higher tolerance to variations in electrode work function or active layer thickness, enabling unique device structures such as planar (vs sandwich) cells with a fully exposed interelectrode gap between identical, inert electrodes .…”

Section: Introductionmentioning

confidence: 99%

Stress Testing Polymer Light‐Emitting Electrochemical Cells: Suppression of Voltage Drift and Black Spot Formation

Gao

2018

Adv Materials Technologies

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The stress characteristics of the polymer light‐emitting electrochemical cells (PLECs) are comprehensively evaluated by varying a host of material and operational parameters. PLECs with the lowest salt concentration of less than 2.5% exhibit runaway voltage drift that leads to rapid cell destruction. PLECs with the lowest electrolyte polymer concentration and a 5% salt content exhibit the longest luminance half‐life, but are slow to activate and are plagued by black spots. At moderate‐to‐high electrolyte concentrations, the PLECs are relatively stable but are not immune to black spots and voltage drift. A lifetime figure‐of‐merit is introduced to quantitatively account for all three indicators of cell degradation in luminance decay, voltage drift, and black spot formation. A surprising discovery is that voltage drift and black spot formation can be effectively suppressed by drastically increasing the electrolyte content. A cell with a 70% electrolyte content exhibits the best lifetime of nearly 350 h when operated at a constant current density of 167 mA cm−2. The black spots can also be effectively eliminated by employing silver instead of aluminum as the cathode material.

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“…In particular, efficient and narrow‐band emissions by QDs have made them attractive candidates for the development of next‐generation LED technologies. WLEDs can also be fabricated through combination of QDs emitting different colors . However, there is considerable room for improvement in terms of color purity, stability, efficiency, and production cost.…”

Section: Optical Properties Of Cdzns/zns Cdznses/zns and Cdse/cds/zmentioning

confidence: 99%

Highly Luminescent Quantum Dots in Remote‐Type Liquid‐Phase Color Converters for White Light‐Emitting Diodes

Choi

Han

et al. 2018

Adv Materials Technologies

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QDs. [14][15][16][17] However, they have less than optimal optical properties due to nonradiative recombination by defects. [12,18] As a result, despite the safety issues, Cdbased QDs are still attracting much attention and are seen as promising candidate materials for versatile applications in nonbiological environments owing to their outstanding performance with respect to tunable luminescence across the ultraviolet-visible-near-infrared (UV-vis-NIR) region, broad absorption bands with narrow emission bands, high quantum yields, [19] chemical stability, and photostability. [20,21] It is important to note that QDs have been passivated with higher bandgap semiconductor layers, such as ZnS and CdS, to increase the quantum yield. In the core-shell type QDs, the shell provides physical and chemical stabilities, as well as photostability to the core QDs, which is important for minimizing cytotoxicity, and also offers platforms for ligand exchange and further functionalization. [22] White light-emitting diodes (WLEDs) are commonly fabricated by combining inorganic phosphors with a blue or UV LED. [23,24] However, it is not easy to achieve a tailored and fullspectrum white light with currently available phosphors. The light spectra emitted by phosphor-based WLEDs are tuned by adjusting weight ratios of phosphors with different emission wavelengths. QDs behave like phosphors but their emissive colors are controlled by varying the size and composition. QDs have emerged as a good alternative to the phosphors in LEDs. Quantum dots (QDs) can be integrated into a solid-phase color converter (SCC) for white light-emitting diodes (WLEDs). However, the development of QD-based SCCs is prevented by the limitations of the QDs themselves, nonuniform dispersion or aggregation of the QDs, and heat accumulation by low thermal conductivity of the solid matrix. Herein, the development of new high-quality CdZnSeS/ZnS QDs in a one spot synthesis is reported that have high photoluminescence quantum yield (up to 100% for green wavelengths), narrow emission spectra (full width at half maximum< 27.3 nm), and good color tunability in the green region, 496-586 nm. Seven different color QDs are used to fabricate liquid-phase color converters (LCCs) for application in WLEDs with a remote configuration. The best LCC-based WLEDs show not only intense bright day white light (correlated color temperature = 6029 K) with a maximum luminous efficacy of 222.7 lm W −1 , but also excellent color quality (color rendering index = 95.1, as well as R9 = 94.4, and R13 = 97.1), which is very important in medical diagnostic lighting, dressing and display room lighting, painting and accent lighting. These results indicate remarkable progress both in the synthesis of high-quality QDs and in the development of WLEDs for high-performance commercial lighting devices.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/admt.201800235.Semiconductor nanocrystals, namely quantum dots (QDs) have created many innova...

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CuInS₂‐Based Quantum Dot Light‐Emitting Electrochemical Cells (QLECs)

Cited by 26 publications

References 60 publications

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Stress Testing Polymer Light‐Emitting Electrochemical Cells: Suppression of Voltage Drift and Black Spot Formation

Highly Luminescent Quantum Dots in Remote‐Type Liquid‐Phase Color Converters for White Light‐Emitting Diodes

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CuInS2‐Based Quantum Dot Light‐Emitting Electrochemical Cells (QLECs)

Cited by 26 publications

References 60 publications

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Efficient and Saturated Red Light‐Emitting Electrochemical Cells Based on Cationic Iridium(III) Complexes with EQE up to 9.4 %

Stress Testing Polymer Light‐Emitting Electrochemical Cells: Suppression of Voltage Drift and Black Spot Formation

Highly Luminescent Quantum Dots in Remote‐Type Liquid‐Phase Color Converters for White Light‐Emitting Diodes

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CuInS₂‐Based Quantum Dot Light‐Emitting Electrochemical Cells (QLECs)