Organic Electroluminescent Device With Variable Hole Transport Layer Thickness
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Solution Overview
Problem
Conventional organic electroluminescent devices with microcavity structures face issues of brightness decline and color deviation at large viewing angles due to the wide wavelength range of organic luminescent materials and the need for precise thickness adjustments of hole transport regions.
Innovation Solution
The organic electroluminescent device incorporates a hole transport layer with multiple portions of different thicknesses in the projection region of each light emitting region, allowing for selective wavelength range enhancement and reduced color deviation by forming multiple microcavities of varying lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity structure with uniform hole transport layer thickness is used, then the device structure is simple and easy to manufacture, but the light intensity is insufficient and color deviation occurs at large viewing angles
Solution Approach 1:
The hole transport layer is designed with different thicknesses in different regions (first thickness in first region, second thickness in second region) to create localized optical cavities with different resonant wavelengths. This local variation in thickness allows different regions to enhance different color wavelengths, solving the color deviation problem while maintaining overall structural simplicity
Solution Approach 2:
The hole transport layer is segmented into multiple regions with different thicknesses, creating multiple independent microcavity structures within a single layer. Each segment acts as an independent optical resonator for wavelength selection, enabling simultaneous enhancement of multiple color channels without requiring separate layers for each color
2Measurement precision
If the hole transport layer thickness is adjusted to select specific wavelength ranges, then color accuracy is improved, but brightness declines at large viewing angles
Solution Approach 1:
By creating regions with different hole transport layer thicknesses, the patent achieves wavelength-specific enhancement in each region while the overall device maintains high brightness through the combined effect of all regions. The local thickness variation creates constructive interference for specific wavelengths without sacrificing total light output
3Ease of manufacture
If a single uniform hole transport layer thickness is used, then the device is easy to manufacture, but color deviation occurs at large viewing angles
Solution Approach 1:
The patent implements local thickness variation in the hole transport layer to achieve color accuracy for different viewing angles. Different thickness regions compensate for viewing angle-dependent color shifts by enhancing specific wavelengths in different spatial zones, maintaining color fidelity across the viewing cone
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
This design enhances light intensity and reduces color deviation while maintaining brightness, improving the overall performance of the organic electroluminescent device by allowing for the selection and enhancement of specific wavelength ranges.
Implementation Method 1
the hole transport layer has at least two portions of different thicknesses for selecting a wavelength range of light emitted by the at least one light emitting region and/or enhancing the emitted light
Data Source
AI summary
This disclosure relates to an organic electroluminescent device, comprising: a light emitting layer comprising a plurality of light emitting regions arranged in an array, each light emitting region being an organic electroluminescent region; an electron transport layer, a cathode and a transflective layer successively disposed in a first direction from the light emitting layer towards a light emergent side of the organic electroluminescent device starting from the light emitting layer; and a hole transport layer, an anode and a reflective layer successively disposed in a second direction opposite to the first direction starting from the light emitting layer. In addition, in a projection region of at least one light emitting region on the hole transport layer, the hole transport layer has at least two portions of different thicknesses for selecting a wavelength range of light emitted by the at least one light emitting region and/or enhancing the emitted light.