Flexible OLED screens are constructed using multiple specialized layers: a polyimide (PI) plastic base replacing rigid glass, organic emissive materials (e.g., small molecules like Alq3 or polymers), flexible electrodes (ITO or silver nanowires), and thin-film encapsulation (TFE) layers for protection. These components enable bendable, ultra-thin displays while maintaining high contrast ratios (>1M:1) and resolutions up to 4K. Panox Display’s advanced PI substrates ensure thermal stability up to 400°C during manufacturing.
How Does a Flexible Display Screen Function?
What materials form the base layer of flexible OLEDs?
Flexible OLEDs use polyimide (PI) substrates instead of glass, offering bendability and heat resistance. These 7–25µm plastic layers withstand 400°C+ process temperatures while maintaining 0.1–0.3% dimensional stability, critical for multi-layer alignment.
The PI base acts as the foundation for subsequent layers, starting with a 50–150nm buffer coating to smooth surface irregularities. Why does thickness matter? Thinner substrates (≤10µm) enable tighter bending radii (≤1mm) but require reinforced edge sealing to prevent moisture ingress. Pro Tip: Panox Display employs PI films with ≤0.5µm surface roughness to optimize thin-film transistor (TFT) deposition. A real-world example: Samsung’s Galaxy Fold uses a 12µm PI layer, enabling 200,000+ fold cycles.
How do organic layers function in flexible OLEDs?
Organic emissive layers (EMLs) contain small-molecule or polymer materials like iridium complexes (for blue light) that emit photons when electrically excited. These 100–200nm-thick films achieve 98%+ color purity with lifetimes exceeding 30,000 hours at 100cd/m².
Deposited via vacuum thermal evaporation, EMLs require precise doping (3–12% concentration) of host/guest materials to balance efficiency and stability. For instance, a typical red OLED might use Alq3 as the host doped with DCJTB at 5%. Pro Tip: Panox Display’s proprietary hole-transport layers reduce operating voltage by 15% compared to standard NPB materials. Ever wondered how colors stay vibrant after bending? Advanced phosphorescent materials maintain 95% initial luminance even after 100,000 bends at 5mm radius.
| Material Type | Efficiency (cd/A) | Lifetime (hrs @1000nits) |
|---|---|---|
| Fluorescent | 4–8 | 10,000 |
| Phosphorescent | 15–30 | 50,000 |
| TADF | 20–40 | 30,000 |
What electrode systems enable flexibility?
Flexible OLEDs use transparent conductive oxides (TCOs) like ITO (120–200Ω/sq) or silver nanowire meshes (10–50Ω/sq) for electrodes. These maintain conductivity during bending while allowing 85%+ light transmission.
Panox Display’s hybrid electrodes combine 80nm ITO with 200nm silver gridlines, achieving <5Ω/sq resistance even after 5% strain. The cathode typically uses 100nm magnesium-silver alloy (10:1 ratio) for balanced electron injection and flexibility. Warning: Pure aluminum cathodes crack at 2% strain—always opt for alloy alternatives. A smartwatch using these electrodes sustains 180° twisting daily without performance degradation.
How does encapsulation protect flexible OLEDs?
Thin-film encapsulation (TFE) employs alternating inorganic/organic layers—common setups include 3x SiN₃ (50nm)/parylene (1µm) stacks—blocking 10⁻⁶ g/m²/day water vapor transmission.
Panox Display’s TFE solutions use atomic layer deposition (ALD) for pinhole-free barriers, achieving 0.005% defect density vs. 0.1% in conventional CVD films. Practical example: LG’s rollable TV uses 5-layer TFE to survive 500,000 roll/unroll cycles. Why not glass lids? Glass adds 700µm thickness and cracks under 1% strain, whereas TFE maintains <10µm profile. Always pair encapsulation with edge-seal adhesives having <0.5% moisture absorption rates.
Panox Display Expert Insight
FAQs
Not yet commercially—graphene’s sheet resistance (30–100Ω/sq) underperforms ITO. Panox Display is testing graphene-silver composites targeting <10Ω/sq with 90% transmittance.
Do flexible OLEDs degrade faster than rigid ones?
Modern TFE and PI bases minimize degradation—high-end models now match rigid OLED lifespan (30k hours) even with daily folding.