Flexible Light Emitting Element Glass Substrate Positioning
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Solution Overview
Problem
Glass substrates in flexible organic light emitting elements tend to crack when bent due to tensile stress, which limits their flexibility and reliability, especially when compared to inorganic moisture-proof layers that can reduce stress effectively.
Innovation Solution
The glass substrate is arranged in a flexible plate-like portion of the light emitting element such that a compressive stress is applied to a portion closer than half the thickness from the concave surface, reducing tensile stress and enhancing flexibility by controlling the bending direction and position of the glass substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass substrate is used in a flexible organic light emitting element, then moisture and oxygen protection is improved, but cracking occurs when bent due to tensile stress
Solution Approach 1:
The patent changes the stress state parameter of the glass substrate from tensile to compressive by controlling its position within the plate-like portion. By positioning the glass substrate such that its thickness direction extends from the concave surface toward the center of the plate-like portion thickness, the glass substrate experiences compressive stress during bending instead of tensile stress, thereby preventing cracking while maintaining moisture and oxygen protection.
2Ease of operation
If the glass substrate is positioned closer to the convex surface, then flexibility is improved, but tensile stress increases causing cracking
Solution Approach 1:
The patent changes the positional parameter of the glass substrate within the plate-like portion. Specifically, it positions the glass substrate such that its thickness direction extends from the concave surface (first surface) toward the center of the plate-like portion thickness, ensuring the glass substrate resides in the compressive stress region during bending. This positional adjustment transforms the stress state from tensile to compressive, enabling flexibility without cracking.
3Strength
If the glass substrate thickness is increased, then strength and crack resistance are improved, but flexibility deteriorates
Solution Approach 1:
The patent changes the stress state parameter of the glass substrate from tensile to compressive through positional control. By positioning the glass substrate to experience compressive stress during bending, the invention enables the use of thicker glass substrates that provide adequate crack resistance while maintaining flexibility, as compressive stress prevents crack propagation that would otherwise occur under tensile stress.
Data Source
AI summary
A light emitting element includes a flexible plate-like portion, and a fixation member fixing the flexible plate-like portion. The flexible plate-like portion includes a light extraction film, a sealing layer, an organic functional layer including a light emitting layer, a glass substrate, and a resin layer having a thickness greater than that of the glass substrate. The fixation member fixes the flexible plate-like portion such that the flexible plate-like portion includes a concave surface and a convex surface opposite to the concave surface, and such that the glass substrate is positioned on a side of the concave surface relative to the resin layer. A center of a thickness direction of the glass substrate is closer to the concave surface than a center of a thickness direction of the flexible plate-like portion is.