White OLED Stacks with Charge Generation Layers
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Solution Overview
Problem
White organic light emitting devices suffer from low luminous efficiency, high power consumption, and limited color viewing angle due to the critical value of luminous efficiency provided by each emission layer and the optical path thickness, leading to inadequate performance in multi-layer structures.
Innovation Solution
A white organic light emitting device with at least two charge generation layers and three stacks, where the first stack includes a blue emission layer, the second stack includes a yellow-green emission layer, and the third stack includes a red and blue emission layer, optimizing the wavelength ranges and number of emission layers to improve luminous efficiency and color viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-layer structures with two or three stacks are provided to improve luminous efficiency, then luminous efficiency is improved, but power consumption increases and luminance decreases
Solution Approach 1:
The device is divided into three distinct stacks, each containing emission layers with specific wavelength ranges (blue: 440-470nm, yellow-green: 530-570nm, red: 590-620nm). This segmentation allows each stack to be optimized independently for luminous efficiency while collectively achieving high overall efficiency and low power consumption
Solution Approach 2:
Different emission layers within each stack are assigned specific wavelength ranges and material compositions tailored to their local function. The first stack uses blue emission layers (440-470nm), the second stack uses yellow-green emission layers (530-570nm), and the third stack uses red emission layers (590-620nm), creating local optimization that improves overall luminous efficiency without increasing power consumption
2Illumination intensity
If emission layers are provided in multi-layer structures to achieve white light emission, then white light emission is achieved, but color viewing angle is limited
Solution Approach 1:
The patent transitions from a single-layer or two-stack structure to a three-stack structure with multiple emission layers at different wavelength ranges. This dimensional expansion in the stack architecture enables simultaneous achievement of white light emission across multiple spectral bands and improved color viewing angle through optimized optical path thickness
Solution Approach 2:
The optical path thickness of each emission layer is specifically optimized to enhance color viewing angle. By adjusting the thickness parameters of the emission layers in each stack, the device achieves improved color uniformity and viewing angle characteristics while maintaining white light emission
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 results in a white organic light emitting device with improved luminous efficiency, reduced power consumption, and enhanced color viewing angle, as demonstrated by lower drive voltage and increased panel efficiency.
Implementation Method 1
An organic light emitting device includes a first stack, a first charge generation layer, a second stack, a second charge generation layer, and a third stack which are sequentially arranged between a first electrode and a second electrode
Data Source
AI summary
Disclosed herein is a white organic light emitting device including various emission layers with improved luminous efficiency, an increased color viewing angle, and low power consumption. The white organic light emitting device includes at least two charge generation layers and at least three stacks between a first electrode and a second electrode. The first stack includes an emission layer having a wavelength range of about 440 to about 470 nm, the second stack includes an emission layer having a wavelength range of about 530 to about 570 nm, and the third stack includes an emission layer having a wavelength range of about 590 to about 620 nm and an emission layer having a wavelength range of about 440 to about 470 nm.