20.2: Ultra‐Bright, Highly Efficient, Low Roll‐Off Inverted Quantum‐Dot Light Emitting Devices (QLEDs)

Dong, Yajie; Caruge, Jean-Michel; Zhou, Ziwu; Hamilton, C.A.; Popović, Zoran V.; Ho, Jia Shin; Stevenson, Matthew; Liu, Guo; Bulović, Vladimir; Bawendi, Moungi G.; Kazlas, Peter T.; Steckel, Jonathan S.; Coe‐Sullivan, Seth

doi:10.1002/sdtp.10462

Cited by 70 publications

(62 citation statements)

References 38 publications

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“…In particular, our group has reported ultrabright and efficient deep red QLEDs. 7 As shown in Fig. 1, the devices demonstrate peak emission wavelength of 620 nm, narrow bandwidth of 22 nm and can achieve high current efficiency (20.5 Cd/A at~20 000 Cd/m 2 ) and small efficiency roll-off at high driving current density.…”

Section: Background For Quantum Dot Light Emitting Devices and Photommentioning

confidence: 90%

“…Among QLEDs of various colors, red QLEDs are currently most advanced and have demonstrated efficiency and brightness that rival or beat state‐of‐the‐art thermal‐evaporated red OLEDs, with narrow peak linewidths in the 20 to 30‐nm range. In particular, our group has reported ultrabright and efficient deep red QLEDs . As shown in Fig.…”

Section: Background For Quantum Dot Light Emitting Devices and Photommentioning

confidence: 99%

“…(c) Luminance and current density versus driving voltage and (d) luminous efficacy and current efficiency versus driving current density for typical devices. Adapted from data in reference …”

Section: Background For Quantum Dot Light Emitting Devices and Photommentioning

confidence: 99%

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Quantum dot light emitting devices for photomedical applications

Chen

Lanzafame

et al. 2017

J Soc Info Display

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While OLEDs have struggled to find a niche lighting application that can fully take advantage of their unique form factors as thin, flexible, lightweight and uniformly large-area luminaire, photomedical researchers have been in search of low-cost, effective illumination devices with such form factors that could facilitate widespread clinical applications of photodynamic therapy (PDT) or photobiomodulation (PBM). Although existing OLEDs with either fluorescent or phosphorescent emitters cannot achieve the required high power density at the right wavelength windows for photomedicine, the recently developed ultrabright and efficient deep red quantum dot light emitting devices (QLEDs) can nicely fit into this niche. Here, we report for the first time the in-vitro study to demonstrate that this QLED-based photomedical approach could increase cell metabolism over control systems for PBM and kill cancerous cells efficiently for PDT. The perspective of developing wavelength-specific, flexible QLEDs for two critical photomedical fields (wound repair and cancer treatment) will be presented with their potential impacts summarized. The work promises to generate flexible QLED-based light sources that could enable the widespread use and clinical acceptance of photomedical strategies including PDT and PBM.

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Section: Background For Quantum Dot Light Emitting Devices and Photommentioning

confidence: 90%

Section: Background For Quantum Dot Light Emitting Devices and Photommentioning

confidence: 99%

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Quantum dot light emitting devices for photomedical applications

Chen

Lanzafame

et al. 2017

J Soc Info Display

Self Cite

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“…As a result, the efficiency roll-off was significantly eliminated and the EQE reached 20%, which is the theoretical maximum for planar devices without extraction features. To address the efficiency roll-off issue, Dong et al recently proposed the use of a Cs 2 CO 3 layer for hole-blocking together with an electron injecting a ZnO nanoparticle layer [75]. This redemitting device surpassed the brightness of organic LEDs at a value of 165,000 cd/m 2 at 1000 mA/cm 2 current density.…”

Section: Electroluminescent Devices Of Colloidal Materials For Lightingmentioning

confidence: 99%

Colloidal nanocrystals for quality lighting and displays: milestones and recent developments

Erdem

Demir

2016

Nanophotonics

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Recent advances in colloidal synthesis of nanocrystals have enabled high-quality high-efficiency light-emitting diodes, displays with significantly broader color gamut, and optically-pumped lasers spanning the whole visible regime. Here we review these colloidal platforms covering the milestone studies together with recent developments. In the review, we focus on the devices made of colloidal quantum dots (nanocrystals), colloidal quantum rods (nanorods), and colloidal quantum wells (nanoplatelets) as well as those of solution processed perovskites and phosphor nanocrystals. The review starts with an introduction to colloidal nanocrystal photonics emphasizing the importance of colloidal materials for light-emitting devices. Subsequently, we continue with the summary of important reports on light-emitting diodes, in which colloids are used as the color converters and then as the emissive layers in electroluminescent devices. Also, we review the developments in color enrichment and electroluminescent displays. Next, we present a summary of important reports on the lasing of colloidal semiconductors. Finally, we summarize and conclude the review presenting a future outlook.

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“…Although the majority of the aforementioned studies to improve charge balance have shown notable achievements in the device performances, sophisticated efforts such as researching an efficient interfacial treatment to block excess electrons without chemically harming the bottom layer or precisely controlling the inserted insulating layer thickness are indispensable . Thus, we focus on a simple and low‐cost method using a metal‐doped ZnO ETL to suppress excess electron injection and improve the device performance.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

et al. 2018

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Charge balance between electrons and holes, which are injected into the quantum dot (QD) emission layer (EML), is critical for realizing stable and efficient QD light‐emitting diodes (QLEDs). ZnO has been widely used as an electron‐transport layer (ETL) because of its superior performance compared to other metal oxides. However, nearly barrier‐free electron injection into the QD EML leads to spontaneous charge transfer and excess electron injection, resulting in reduced device performance. Here, to adjust electron–hole balance and thereby improve the lifetime and efficiency of QLEDs, we introduce an yttrium (Y)‐doped ZnO (YZO) ETL into QLEDs. The sol–gel processed YZO film, with a mobility that could be simply tuned by varying the Y concentration, provides enhanced charge‐transport balance by suppressing excess electron flow to the QD EML. Furthermore, YZO helps suppress QD charging and smooth the surface morphology. Applying the YZO ETL into the inverted‐structure QLED enables us to achieve color‐saturated red emission, an improved external quantum efficiency of up to 8.6%, and an eight times longer lifetime compared to the device with undoped ZnO. This result provides a simple method for enhancing the performance of QLEDs by easily controlling metal doping concentration in the sol–gel processed ZnO ETL.

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20.2: Ultra‐Bright, Highly Efficient, Low Roll‐Off Inverted Quantum‐Dot Light Emitting Devices (QLEDs)

Cited by 70 publications

References 38 publications

Quantum dot light emitting devices for photomedical applications

Quantum dot light emitting devices for photomedical applications

Colloidal nanocrystals for quality lighting and displays: milestones and recent developments

Enhanced Lifetime and Efficiency of Red Quantum Dot Light‐Emitting Diodes with Y‐Doped ZnO Sol–Gel Electron‐Transport Layers by Reducing Excess Electron Injection

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