Curved OLED Panel Stress Distribution for Bendable Displays
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Solution Overview
Problem
Bendable organic light emitting display devices face deterioration in characteristics due to stress from bending, which affects the connectivity of wiring and performance of layers in the display.
Innovation Solution
A curved organic light emitting display device is designed with a flexible substrate and specific stress distribution, where the thin film transistor layer receives compressive stress, and the organic light emission layer and protective films receive tensile stress, maintaining equilibrium at a neutral plane to minimize deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display device is made bendable using a flexible substrate, then the device can be curved to enable new form factors, but the wiring may be disconnected and layer characteristics may deteriorate due to bending stress
Solution Approach 1:
The patent employs a flexible substrate as the base structure to enable bending capability. Additionally, thin film encapsulation layers are deposited over the organic light emitting layer to provide mechanical flexibility while protecting the underlying layers during bending operations, allowing the device to maintain both bendability and structural integrity
Solution Approach 2:
The patent uses a composite structure combining organic light emitting materials with inorganic encapsulation layers (such as aluminum oxide, silicon oxide, or silicon nitride). This composite approach allows the organic layer to provide light emission functionality while the inorganic layers provide mechanical strength and stress distribution during bending, resolving the contradiction between flexibility and reliability
2Device complexity
If the thin film transistor layer is positioned to receive tensile stress during bending, then the structure may be simpler, but the semiconductor layer characteristics deteriorate due to tensile stress
Solution Approach 1:
The patent strategically positions the thin film transistor layer containing the semiconductor layer at a specific location within the device structure where it experiences compressive stress or neutral stress during bending, rather than tensile stress. This localized stress management protects the sensitive semiconductor characteristics while maintaining overall device functionality and simplicity
3Strength
If protective films and adhesive layers are added to protect the organic light emitting layer, then the device becomes more robust against stress, but the device complexity increases
Solution Approach 1:
The patent applies thin film encapsulation layers that are sufficiently thin to maintain flexibility and minimize added complexity, yet thick enough to provide adequate protection against bending stress. The adhesive layers are also optimized to provide necessary bonding strength without excessive thickness that would increase device complexity. This partial action approach achieves adequate protection while minimizing the impact on device simplicity
Data Source
AI summary
An organic light emitting display device includes: a curved organic light emitting display panel. The organic light emitting display panel includes a flexible substrate, a thin film transistor layer including a semiconductor layer, and an organic light emission layer including an organic light emitting material. In the curved organic light emitting display panel, the thin film transistor layer receives a compressive stress, or a neutral plane in which the compressive stress and a tensile stress maintain equilibrium is defined in the thin film transistor layer.