OLED Sealing via Graded Thermal Expansion Buffer
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Solution Overview
Problem
Conventional OLED devices face degradation due to sensitivity to oxygen and moisture, and developing a complete sealing process to prevent leakage is challenging, which affects their effective lifetime.
Innovation Solution
A light emitting device design featuring a first substrate with an illuminating member, a protective layer, a buffer member with a specific coefficient of thermal expansion (CTE) between the substrates, and a sealant with an even lower CTE to create a sealed environment, using materials like acrylic resin, epoxy resin, and glass frit to prevent moisture and oxygen ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing processes are used to seal the OLED device, then the organic layer and electrode are protected from oxygen and moisture, but the sealing process is difficult to develop and may not achieve complete sealing
Solution Approach 1:
The patent applies parameter changes by carefully selecting materials with specific coefficients of thermal expansion (CTE) for the protective layer, buffer member, and sealant. The CTE values are ordered such that CTE(protective layer) > CTE(buffer member) > CTE(sealant), creating a gradient structure that accommodates thermal stress and prevents seal failure during temperature variations, thereby achieving reliable sealing without complex processes
Solution Approach 2:
The patent employs composite materials by using a multi-layer structure consisting of a protective layer, buffer member, and sealant, each made from materials with specific properties. This composite structure combines the advantages of different materials to achieve both protection from environmental factors and ease of manufacturing through a straightforward lamination process
2Duration of action of stationary object
If the organic layer and electrode are completely sealed to prevent oxygen and moisture leakage, then the effective lifetime of OLED devices is significantly increased, but it is very difficult to develop a sealing process to achieve complete sealing
Solution Approach 1:
The patent resolves this contradiction by changing the material parameters, specifically the coefficients of thermal expansion, to create a thermally compatible sealing structure. The graded CTE structure ensures that thermal expansion stresses are distributed evenly, preventing seal failure and achieving complete sealing that extends device lifetime while maintaining manufacturing simplicity
Solution Approach 2:
The buffer member acts as an intermediary between the protective layer and the sealant, mediating the thermal stress transfer. This intermediate layer with intermediate CTE value prevents direct stress concentration at the sealant interface, enabling reliable sealing that protects the organic layer and electrode for extended periods
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 increases the lifetime of OLED devices by creating a robust seal that prevents oxygen and moisture from reaching the organic layer, thereby enhancing their durability and performance.
Implementation Method 1
the buffer member has a second coefficient of thermal expansion which is less than the first coefficient. The sealant surrounds the buffer member and seals off the space between the first and second substrates, wherein the sealant has a third coefficient of thermal expansion which is less than the second coefficient
Data Source
AI summary
Disclosed herein is a light emitting device, which includes a first substrate, a protective layer, a second substrate, a buffer member and a sealant. The first substrate has an illuminating member thereon. The protective layer covers the illuminating member and has a first coefficient of thermal expansion. The second substrate is disposed over the protective layer. The buffer member is disposed between the first and second substrates and surrounds the protective layer, wherein the buffer member has a second coefficient of thermal expansion which is less than the first coefficient. The sealant surrounds the buffer member and seals off the space between the first and second substrates, wherein the sealant has a third coefficient of thermal expansion which is less than the second coefficient.