Light-Emitting Element Red Light Color Purity
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Solution Overview
Problem
Current light-emitting elements with white EL layers struggle to achieve high color purity and efficiency for red light emission, as shifting the emission spectrum to increase color purity leads to decreased emission intensity due to transmission through optical elements.
Innovation Solution
A light-emitting element with an EL layer between a reflective and semi-transmissive electrodes, incorporating a transparent conductive layer and a specific optical element with tailored transmittance, enhances red light emission by adjusting optical path lengths and using a phosphorescent organometallic complex, achieving high color purity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the emission spectrum is shifted to increase color purity, then color purity is improved, but emission intensity decreases due to transmission through optical elements
Solution Approach 1:
The patent changes the emission wavelength parameter to a longer wavelength range (620-680 nm) where optical elements have better transmission characteristics, and optimizes the half width parameter (5-120 nm) to balance color purity and intensity. This parameter optimization resolves the contradiction by finding the optimal emission characteristics that satisfy both color purity and emission intensity requirements
Solution Approach 2:
The patent applies local quality by using a phosphorescent organometallic complex with specific emission characteristics in the EL layer, and combining it with an optical element having specific transmittance characteristics at different wavelength ranges. This localized optimization of emission and transmission properties at the red light wavelength range resolves the contradiction between color purity and emission intensity
2Device complexity
If a white color filter method is used to achieve full color display, then manufacturing complexity is reduced, but color purity decreases
Solution Approach 1:
The patent changes the emission characteristics parameter to achieve intrinsic high color purity red light emission from the EL layer itself, eliminating the need for color filters. By optimizing the phosphorescent complex and emission wavelength, the patent achieves high color purity without additional optical filtering components, thus resolving the contradiction between manufacturing complexity and color purity
Solution Approach 2:
The patent extracts the color filtering function from the optical system by achieving color purity through the emission characteristics of the phosphorescent organometallic complex itself. This eliminates the need for separate color filter components, reducing manufacturing complexity while maintaining high color purity
3Productivity
If red light emission is intensified by adjusting optical path length, then emission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the optical path length parameter to enhance red light emission efficiency by constructive interference effects. By carefully controlling the thickness and refractive index of layers in the EL device, the patent achieves intensified red light emission without adding complex optical components, thus resolving the contradiction between emission efficiency and device complexity
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 enables a light-emitting element with high color purity and low power consumption by intensifying red light emission within a specific wavelength range, combining with an optical element to maintain emission intensity, thus facilitating full-color displays with reduced power consumption.
Implementation Method 1
Light emission from a triplet excited state is referred to as phosphorescence
Implementation Method 2
an EL layer that exhibits white light emission between a pair of electrodes
Data Source
AI summary
A novel light-emitting element is provided. A light-emitting element that emits red light with high color purity and has high emission efficiency is provided. A full-color light-emitting device having low power consumption is provided. In the light-emitting element that exhibits white light emission, the emission wavelength range of red light is a specific range on the longer wavelength side than the conventional emission wavelength range of red light that is usually used, and an optical element having a specific transmittance in the specific wavelength range is used.