Toward 200 Lumens per Watt of Quantum-Dot White-Light-Emitting Diodes by Reducing Reabsorption Loss

Li, Jiasheng; Tang, Yong; Ding, Xinrui; Yu, Binhai; Yu, Shudong; Ou, Jian Zhen; Kuo, Hao‐Chung

doi:10.1021/acsnano.0c05735

Cited by 93 publications

(61 citation statements)

References 65 publications

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“…In the conventional structure, only the light with exit angle smaller than the escape angle can be emitted due to the total internal reflection (TIR) at the encapsulation layer/air interface, resulting in a low light extraction efficiency for the pristine device. [ 21,22 ] In the device with a porous film, the TIR light can be scattered by the porous film homogeneously which increases the possibility of large‐angle light escaping into air and therefore improves the light extraction efficiency of the device. [ 23 ] Figure 5b shows the optical power and wall plug efficiency (WPE) of blue LED devices at various driving currents.…”

Section: Resultsmentioning

confidence: 99%

Biomimetic Porous Fluoropolymer Films with Brilliant Whiteness by Using Polymerization‐Induced Phase Separation

Huang

Fang

et al. 2021

Adv Materials Inter

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Inspired by the Cyphochilus scale with extreme whiteness, fluoropolymer is used as the matrix to prepare highly scattering porous polymer films through polymerization‐induced phase separation (PIPS) method. The mixture used for the PIPS technique contains a fluoride monomer, a UV photoinitiator, and porogens (cyclohexanol and perfluorooctanol). By carefully tuning the mixture parameters (cyclohexanol–perfluorooctanol and monomer–porogen weight ratios), the porous morphology can be well tailored, which induces different scattering performances. With an optimized formulation (50 wt% monomer, 25 wt% cyclohexanol, and 25 wt% perfluorooctanol), the porous film with a thickness of 55 µm can achieve an average total reflectance of ≈90%, featuring a measured transport mean free path of 1.3–1.7 µm (comparable to the 1.5 µm of the benchmark Cyphochilus scale). Further, the porous films are applied to the light‐emitting diode (LED) device and it is demonstrated that they can effectively improve the light extraction efficiency of the LED and thus enhance the luminous performance. Due to the simplicity, cost‐effectiveness, and scalability of the PIPS method, the as‐developed porous fluoropolymer films with such excellent scattering ability can find many potential applications not only in the field of optoelectronics, but also in various complex scenarios, such as daytime passive radiative cooling.

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Section: Resultsmentioning

confidence: 99%

Biomimetic Porous Fluoropolymer Films with Brilliant Whiteness by Using Polymerization‐Induced Phase Separation

Huang

Fang

et al. 2021

Adv Materials Inter

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“…Among them, the EWD is a new reflective display technology after electrophoretic display technology [6,7]. Compared with conventional display technologies [8,9], the EWD technology has the advantages of low power consumption, high contrast, fast response, and full color [10,11], which is considered one of the most attractive emerging display technologies [12].…”

Section: Introductionmentioning

confidence: 99%

Driving Waveform Optimization by Simulation and Numerical Analysis for Suppressing Oil-Splitting in Electrowetting Displays

2021

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Electrowetting display (EWD) is a new reflective display device with low power consumption and fast response speed. However, the maximum aperture ratio of EWDs is confined by oil-splitting. In order to suppress oil-splitting, a two-dimensional EWD model with a switch-on and a switch-off process was established in this paper. The process of oil-splitting was obtained by applying different voltage values in this model. Then, the relationship between the oil-splitting process and the waveforms with different slopes was analyzed. Based on this relationship, a driving waveform with a narrow falling ramp, low-voltage maintenance, and a rising ramp was proposed on the basis of square waveform. The proposed narrow falling ramp drove the oil to rupture on one side. The low-voltage maintenance stage drove the oil to shrink with a whole block. The proposed rising ramp was pushed the oil into a corner quickly. The experimental results showed that the oil splitting can be suppressed effectively by applying the proposed driving waveform. The aperture ratio of the proposed driving waveform was 2.9% higher than that of the square waveform with the same voltage.

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“…With the development of semiconductor materials and packaging technology, the luminous flux of high-power white LEDs has rapidly improved. The application of LEDs in the automotive lighting field has gradually expanded, from signal indicators to current automotive headlights, reflecting the development trend that LEDs will become the mainstream light source in this field [1][2][3][4]. Flip-chip LEDs (FCLEDs) exhibit excellent heat dissipation performance and high light efficiency, and have been attracting great attention in the field of high-power LEDs.…”

Section: Introductionmentioning

confidence: 99%

Improving the External Quantum Efficiency of High-Power GaN-Based Flip-Chip LEDs by Using Sidewall Composite Reflective Micro Structure

Fan²,

Sun

et al. 2021

Micromachines

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For high-power applications, it is important to improve the light extraction efficiency and light output of the vertical direction of LEDs. Flip-chip LEDs (FCLEDs) with an Ag/SiO2/distributed Bragg reflector/SiO2 composite reflection micro structure (CRS) were fabricated. Compared with the normal Ag-based FCLEDs, the light output power of the CRS-FCLEDs was increased by 6.3% at an operational current of 1500 mA, with the corresponding external quantum efficiency improved by 6.0%. Further investigation proved that the CRS structure exhibited higher reflectance compared with the commonly used Ag-mirror reflective structure, which originates from the increased reflective area in the sidewall and partial area of the n-GaN contact orifices. It exhibited markedly smaller optical degradation and thus higher device reliability as compared to normal Ag-based FCLED. Moreover, the light emission intensity distributions and far-field angular light emission measurements show that the CRS-FCLED has a strengthened light output in the vertical direction, which shows great potential for applications in high-power fields, such as headlamps for automobiles.

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Toward 200 Lumens per Watt of Quantum-Dot White-Light-Emitting Diodes by Reducing Reabsorption Loss

Cited by 93 publications

References 65 publications

Biomimetic Porous Fluoropolymer Films with Brilliant Whiteness by Using Polymerization‐Induced Phase Separation

Biomimetic Porous Fluoropolymer Films with Brilliant Whiteness by Using Polymerization‐Induced Phase Separation

Driving Waveform Optimization by Simulation and Numerical Analysis for Suppressing Oil-Splitting in Electrowetting Displays

Improving the External Quantum Efficiency of High-Power GaN-Based Flip-Chip LEDs by Using Sidewall Composite Reflective Micro Structure

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