Light-Emitting Device UV Protection via Composite Encapsulation
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Solution Overview
Problem
Light-emitting devices are vulnerable to damage from external ultraviolet light, which can degrade the emission layer and other organic materials, especially when used outdoors or during manufacturing processes that involve UV irradiation.
Innovation Solution
Incorporating a thin film encapsulation portion with a cured organic film composition that includes a UV absorber, along with a color conversion layer using quantum dots, to reduce the transmission of ultraviolet light and enhance the device's UV blocking capabilities, while maintaining low driving voltage and high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thin film encapsulation portion with UV absorber is added to block ultraviolet light, then UV protection capability is improved, but device structure complexity increases
Solution Approach 1:
The patent combines the encapsulation function and UV absorption function into a single thin film encapsulation portion. The organic film in this encapsulation layer contains a UV absorber, allowing it to simultaneously protect the light-emitting device from environmental factors (encapsulation) and block ultraviolet light (UV absorption), thereby improving UV protection capability without significantly increasing structural complexity
Solution Approach 2:
The thin film encapsulation portion uses composite material composition by incorporating a UV absorber into the organic film matrix. This composite structure enables the material to exhibit both the properties of the base organic film (encapsulation, flexibility, transparency) and the UV absorption properties of the added UV absorber compound, achieving dual functionality in a single layer
2Adaptability or versatility
If multiple emission units with different emission wavelengths are stacked, then color display capability is improved, but manufacturing complexity increases
Solution Approach 1:
The light-emitting device is segmented into multiple emission units stacked vertically, with each unit responsible for emitting a specific wavelength range (red, green, blue). This segmentation allows each unit to be optimized independently for its specific emission characteristics while working together to provide full-color display capability. The charge generating layers are also segmented into n-type and p-type layers between adjacent emission units
Solution Approach 2:
Instead of arranging different color emission units side by side in a planar configuration, the patent stacks them vertically in the thickness direction. This dimensional change from 2D lateral arrangement to 3D vertical stacking reduces the lateral area required and simplifies the interconnection structure, as all emission units share common electrode structures (first and second electrodes) rather than requiring separate interconnections for each unit
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 effectively protects the light-emitting device from UV damage, ensuring long lifespan and high light stability by absorbing UV light and preventing its penetration, thus maintaining the device's performance and longevity.
Implementation Method 1
the composition comprising a curable material and an ultraviolet (UV) absorber
Implementation Method 2
a color conversion layer using quantum dots
Implementation Method 3
Carriers, such as holes and electrons, may then recombine in the emission layer to produce excitons. These excitons transition from an excited state to a ground state, thereby generating light.
Data Source
AI summary
A light emitting device includes: a first electrode; a second electrode facing the first electrode; m emission units stacked between the first electrode and the second electrode; and m−1 charge generating layer(s) between the two adjacent emission units from among the m emission units, m−1 charge generating layer(s) including m−1 n-type charge generating layer(s) and m−1 p-type charge generating layer(s), wherein m is an integer of 2 or greater, a maximum emission wavelength of light emitted from at least one of the m emission units differs from that of light emitted from at least one of the other emission units, at least one of the m−1 n-type charge generating layer(s) includes a metal-containing material and an electron transporting metal-non-containing material.