Abstract
We report an effective method to extract light from quantum-dot light emitting diodes (QLEDs) by embedding an internal nano-scattering pattern structure. We use finite-difference time-domain method to analyze the light extraction efficiency of red QLEDs with periodic, quasi-random, and random internal nano-scattering pattern structures. Our simulation results indicate that random internal nano-scattering pattern can greatly enhance the outcoupling efficiency while keeping wide viewing angle for the red QLED. Similar results are obtained by extending this approach to green and blue QLEDs. With the proposed red, green, and blue QLEDs combination, we achieve 105.1% Rec. 2020 color gamut in CIE 1976 color space. We demonstrate that internal nano-scattering pattern structures are attractive for display applications, especially for enhancing the outcoupling efficiency of blue QLEDs.
Highlights
Colloidal quantum dots (QDs) exhibit several attractive features, such as high quantum efficiency, tunable emission wavelength through particle size control, and narrow emission bandwidth which leads to vivid colors [1,2]
We find that internal nano-scattering pattern can effectively extract light from quantum-dot light emitting diodes (QLEDs)
By comparing the outcoupling efficiency and viewing angle of the red QLED with periodic, quasi-random, and random internal nano-scattering pattern, we find that the random internal nano-scattering pattern is the prominent candidate among these three designs for QLED applications
Summary
Colloidal quantum dots (QDs) exhibit several attractive features, such as high quantum efficiency, tunable emission wavelength through particle size control, and narrow emission bandwidth which leads to vivid colors [1,2]. The first study offering detailed insight into the light extraction efficiency enhancement of QLED devices came out recently by introducing large-scale nanopillar arrays on the surface of glass substrate [21] This approach opens up a new window to improve the optical performances of OLEDs with small pixel sizes. The optimal pattern style can be selected from among periodic, quasi-random, and random internal nano-scattering patterns by systematically analyzing the outcoupling efficiency as well as the radiated pattern of a patterned QLED We extend this approach to green and blue QLEDs and compare the obtained color gamut in both CIE1976 and CIE1931 for the patterned and non-patterned QLEDs with that proposed by ITU-R Recommendation BT.2020, namely Rec. 2020, for ultra-high definition televisions [22]. This analysis demonstrates the feasibility of QLED display with internal nano-scattering pattern
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