InP Quantum Dot Light Absorption Layer for BT.2020 Color Reproduction
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Solution Overview
Problem
Cd-free InP based quantum dot light-emitting devices face limitations in achieving high light emission efficiency and wide color reproduction range, with existing technologies only allowing for less than 80% color reproduction in BT.2020 ratio due to broad light emission spectrums.
Innovation Solution
Incorporating a light absorption layer that selectively absorbs light at 570 to 610 nm between the light-emitting layers, which are composed of InP based quantum dots, to reduce the tail of the light emission spectrum and enhance color separation, thereby increasing the color reproduction range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If InP based quantum dots are used as light-emitting layers, then the device is Cd-free and has high light emission efficiency, but the color reproduction range is insufficient (less than 80% in BT.2020 ratio)
Solution Approach 1:
A light absorption layer is introduced as an intermediary component between the light-emitting layers and the light extraction surface. This layer selectively absorbs light in the 570-610 nm wavelength range, which corresponds to the yellow-orange region of the spectrum. By removing this specific wavelength range, the light absorption layer sharpens the overall light emission spectrum and improves color separation, enabling the device to achieve a color reproduction range of 80% or more in BT.2020 ratio while maintaining the Cd-free and high efficiency characteristics of the InP quantum dots
Solution Approach 2:
The patent modifies the optical parameters of the light emission spectrum by introducing the light absorption layer with specific absorption characteristics (570-610 nm wavelength range). This parameter change in the spectral distribution sharpens the emission spectrum and expands the color reproduction range, transforming the device performance from less than 80% BT.2020 ratio to 80% or more while preserving the underlying InP quantum dot light-emitting layers
2Adaptability or versatility
If the light emission spectrum is broad to cover more colors, then the color reproduction range increases, but the light emission efficiency decreases
Solution Approach 1:
The light absorption layer extracts or removes specific unwanted wavelengths (570-610 nm) from the broad light emission spectrum generated by the InP quantum dots. By taking out this specific wavelength range that contributes to spectral broadening without adding value to color reproduction, the patent sharpens the overall spectrum and improves color separation. This extraction process maintains high light emission efficiency while achieving the required color reproduction range of 80% or more in BT.2020 ratio
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a Cd-free light-emitting device with high light emission efficiency and a wide color reproduction range, exceeding 80% in BT.2020 ratio, by sharpening the light emission spectrums and improving color separation.
Implementation Method 1
a light absorption layer disposed between the plurality of light-emitting layers and a light extraction surface, wherein the light absorption layer selectively absorbs light at 570 to 610 nm
Data Source
AI summary
A light-emitting device includes: an anode electrode; a cathode electrode; a plurality of light-emitting layers sandwiched between the anode electrode and the cathode electrode; and a light absorption layer disposed between the plurality of light-emitting layers and a light extraction surface, wherein the plurality of light-emitting layers include InP based quantum dots and are configured to emit at least green color of light and red color of light, and the light absorption layer selectively absorbs light at 570 to 610 nm.