Opportunity
Flexible display glass, such as ultra-thin glass used in foldable and rollable screens, suffers from inherently low surface ductility. Under tensile stress during bending, the material undergoes plastic deformation and eventually develops micro-cracks or even catastrophic fractures. This brittleness forces designers to use large bending radii, limiting the form factor of devices and compromising mechanical performance. Moreover, sharp glass fragments from broken screens pose serious safety hazards to users. Existing solutions struggle to simultaneously achieve high mechanical strength, high toughness, high transparency, and cost-effective mass production. There is a pressing need for a protective layer that enhances surface ductility and crack resistance of flexible glass without sacrificing optical clarity or adding prohibitive manufacturing complexity.
Technology
This patent presents a bendable display device comprising a display glass panel and a transparent protective film deposited directly on it. The protective film is a multilayer metal oxide nanostructure—arranged in a sandwich-like configuration—with a thickness below 1000 nm and a transmittance of at least 93%. The metal oxide can be indium tin oxide, aluminum-doped zinc oxide, or indium-doped cadmium oxide. The film is formed by physical vapor deposition (PVD): the metal oxide nanostructures are vaporized and condensed onto the glass panel, creating a uniform, ultra-tough coating. To further enhance performance, the glass substrate undergoes an ion-exchange chemical treatment (e.g., immersion in a molten potassium salt bath at ≥300°C) and a plasma treatment (using argon and a reactive gas such as oxygen or nitrogen) before PVD. The resulting bendable display exhibits a surface ductility of at least 50 N and a bending radius of less than 1 mm. This combination of materials and processes solves the long-standing trade-off between mechanical robustness and optical transparency.
Advantages
- Significantly improves surface hardness (from ~7 GPa to over 11.5 GPa).
- Greatly enhances crack resistance (from ~53 N to over 94 N).
- Achieves excellent pencil hardness (≥9H, exceeding the maximum scale of standard test).
- Passes 1000-cycle steel wool abrasion test under 1 kg load with no visible scratches.
- Demonstrates superior scratch resistance (threshold increased from ~16 N to ~18 N).
- Maintains integrity after 20,000 bending cycles at a radius of 1 mm.
- High optical transmittance (≥93%) ensures minimal impact on display quality.
- Thin film (<1000 nm) does not impair flexibility or add significant weight.
- Compatible with commercial PVD processes, enabling cost-effective mass production.
- Uses readily available metal oxide materials and standard ion-exchange/plasma treatments.
Applications
- Foldable smartphones and tablet displays employing ultra-thin glass.
- Rollable or flexible screens for wearable electronics.
- Bendable display panels in automotive dashboards and infotainment systems.
- Curved or flexible touch sensors and cover glass for consumer electronics.
- Protective coatings for any flexible glass substrate used in emerging display technologies.
