Thin Glass Substrate for OLED Light Extraction
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Solution Overview
Problem
OLED lighting devices face low light extraction efficiency due to light reflection at the substrate-transparent electrode interface and require high gas-barrier properties to prevent moisture ingress, while also needing flexibility for curved installations, which resin films struggle to provide.
Innovation Solution
A glass sheet with a thickness of 2 mm or less and a refractive index of 1.55 or more is used as a substrate, composed of 10-60% BaO+TiO2+Nb2O5+La2O3+ZnO+ZrO2, with unpolished surfaces and controlled surface roughness to minimize reflection and enhance gas-barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional substrate with thickness of 0.5 to 0.7 mm is used, then the substrate has sufficient mechanical strength, but light extraction efficiency is low due to reflection at the substrate-transparent electrode interface
Solution Approach 1:
The patent changes the refractive index parameter of the substrate by selecting glass types with nd ≥ 1.55, and adjusts the thickness parameter to 2 mm or less. These parameter changes reduce the refractive index difference at the interface, thereby reducing light reflection and improving extraction efficiency while maintaining mechanical strength
Solution Approach 2:
The patent specifies a composite glass composition containing multiple oxides (BaO, TiO2, Nb2O5, La2O3, ZnO, ZrO2) in specific ranges. This composite material approach allows optimization of both optical properties (refractive index) and mechanical properties (strength) simultaneously, resolving the contradiction between light extraction efficiency and mechanical durability
2Adaptability or versatility
If a resin film is used to enhance flexibility for curved installation, then the substrate becomes flexible, but gas-barrier property is insufficient
Solution Approach 1:
The patent reduces the substrate thickness parameter to 2 mm or less (preferably 0.1 to 1.0 mm), which significantly improves flexibility while maintaining the inherent gas-barrier properties of glass. This parameter change allows the substrate to conform to curved surfaces without compromising moisture protection
Solution Approach 2:
The patent employs a composite glass material containing specific oxide combinations that provide both mechanical flexibility when thin and excellent gas-barrier properties. The multi-oxide composition ensures high reliability against moisture ingress while enabling curved installations
3Adaptability or versatility
If the substrate thickness is reduced to improve flexibility, then the substrate becomes more flexible, but mechanical strength decreases
Solution Approach 1:
The patent uses a composite glass material containing BaO (10-40 mass%), TiO2 (5-20 mass%), Nb2O5 (5-20 mass%), La2O3 (5-20 mass%), ZnO (5-20 mass%), and ZrO2 (5-20 mass%). This specific composite composition provides high mechanical strength even at reduced thicknesses of 2 mm or less, enabling flexibility without sacrificing structural integrity
Solution Approach 2:
The patent optimizes the thickness parameter to a specific range (2 mm or less, preferably 0.1 to 1.0 mm) and combines it with controlled surface roughness (Ra: 0.01 to 10 μm). These parameter changes achieve the desired flexibility while the composite material composition maintains sufficient mechanical strength
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 significantly improves light extraction efficiency and provides high gas-barrier and flexible properties, enabling efficient light emission and reliable operation of OLED lighting devices on both flat and curved surfaces.
Implementation Method 1
the refractive index nd of the glass sheet is 1.55 or more, and hence light emitted from an organic light-emitting layer becomes difficult to reflect at the interface between a substrate and a transparent electrode
Data Source
AI summary
A glass sheet has a thickness of 2 mm or less and has a refractive index nd of 1.60 or more. The glass sheet allows light emitted from an organic light-emitting layer to be efficiently extracted to the outside and has high gas-barrier properties. The glass sheet comprises 15-40 mass % of BaO.