Flexible Printed OLED TV has Potential to Create a New Application Market

The next generation of premium TVs could enable a smarter way thinking, living, and working. THE NEXT GENERATION OF PREMIUM TVS1 (ROLLABLE/foldable) has the potential to create large business opportunity. Flexible printed OLED TV Mobiles, combined with touch/camera technology, ubiquitous connectivity through 5G/6G integration IoT/healthcare sensors (through help AI, big data, iCloud) will smart working (Fig. 1). TCL believes that this kind Mobile be “disruptive game changer” in display industry. Mobiles available commercially near future. But what does game-changing technology entail? Requirements include superb image quality, such as an extremely high contrast ratio (>500,000:1) for dynamic range, resolution (8K), wide color gamut (DCI-P3: >100 percent), true viewing angle (∆u'v’ = 0.02, >+/– 60 degrees), no compromises user experience. This allows viewers watch high-speed moving (MPRT: ∼0.1 ms) without motion blurring. Other requirements screen size (>75 inches); design differentiation (to provide product designer more freedom explore foldable/rollable flexible transparent TV); eco-friendliness (low power consumption [Energy Star Standard] hazardless materials); three dimensions (in future). When considering market TVs, non-emissive-type LCD have difficulty meeting some demands 2), leading shift OLED/quantum-dot LED (QLED) technology. Market trends first demonstrated these capabilities their 31-inch full high-definition (FHD) at Consumer Electronics Show (CES) 2020 3). Since then, panel performance improved drastically based on latest breakthroughs It provides optimization top-emission device architecture, oxide thin-film transistor (TFT) backplane (B/P) advanced encapsulation (31-inch FHD: firmware luminance: 200 nit; >500,000:1; gamut: DCI-P3 >98 percent; dependency (Δu'v’ <0.02): ≥+/– degrees; aperture >50 bending curvature radius: 75 mm). article details technological development status challenges. high-density its performance. Fig. 4 shows process flow architecture FHD TV. TFT B/P etch stopper type is fabricated polyimide layer buffer (SiNx/SiO2 multi-layers) avoid penetration moisture oxygen. then followed by RGB patterning inkjet printing structure top emission which can maximize enhance lifetime panel. consists inorganic (chemical vapor deposition, CVD: SiNx or SiONx) organic (inkjet process: acrylic epoxy resin) multi-layers. In module process, laser lift-off used glass release. Process indium gallium zinc (IGZO) suitable commercializing because terms mobility, stability, scalability manufacturing up G8.5 (2,200 × 2,500 mm2)/G11 (2,940 mm 3,370 mm2) substrates.2, 3 requirement IGZO minimize variation luminance before after release 5). change (I-V curve) comparable. determined current (Ioled 1/2 W/L Ci µ(Vgs-Vth)2). full-white (FW) nits measured (Konica Minolta Spectrophotometer CS2000A), standard deviation calculated. R: 4.85 percent, G: 1.12 B: 1.57 respectively, acceptable TVs. To minimal release, continuously high-resolution 8K, longer panel, there are few key challenges consider. First prospect developing co-planar top-gate excellent stability (positive bias temperature stress [PBTS], negative illumination [NBTIS], [CS]) uniformity G8.5/G11 substrate, creating reliability greater than 1 million times. second thing consider mobility (>30 cm2/v.sec). third external compensation circuit. co-planner including cm2/v.sec) 8K TV, parasitic capacitance, channel length, cost simple compared etch-stopper-type architecture. circuit, 3T1C, also under achieve panels. For new materials gate insulator passivation development. emissive-type next-generation competing technologies: white (WOLED) + filter (CF) technology4 (current mainstream mass production technology), QD-OLED (starting production), pilot special monitor products applications). Table compares technologies displays, capability, competitiveness. technology1, 5-8 multiple benefits only five six layers easily neutral plane (compared WOLED CF contains 20 blue tandem color-conversion red green QD layer, requires two rounds process). capability adopts cathode infrared (IR) drop issues, make (276 ppi) pixel 32 inches. competitive, material usage (>95 percent substrate) productivity air environment (versus vacuum environment). reasons, (IJP) alternative solution technical IJP enhancing establishing mura-free G11 substrates. using emission. ink supplied Mitsubishi Chemical (red green) LG (blue). efficiency long lifetime: getting closer commercial target specification. essential this, flat film formation within crucial. purpose not but maximum If non-uniformity thickness pixel, cannot guaranteed. thinner degraded quickly due concentration parameters follows: First, equipment high-performance print-head (high resolution, volume control scheme, placement accuracy, in-situ analysis system, stage maintenance scheme). Second, formulation (viscosity surface tension, solvent boiling point pressure, solubility, precipitation agglomeration, shelf-life). Third hydrophobic bank (bank material, design, pinning point, contact difference between anode surface, outgassing, contamination). Fourth, strategy (an interlacing assembly throughput, reliable jetting). And fifth dry bake process. 6 optimizing printing. further improvement each line (rather bank) introduced. Based (<+/– 5 Bruker 3D optical microscopy, model Contour GT-I), mura been achieved. (Luminance all pixels: Sigma 0.4 Max 0.9 Konica-Minolta spectrophotometer, CS2000A.) Thickness regard substrates throughput yield, should improve first, percent) accuracy 10 µm); second, print-heads’ high-throughput (TACT: <90 sec/substrate) yield (no particle mixing); third, small (< pl) TV; fourth, easy system footprint (with water transmittance rate [WVTR] humidity [85 relative [RH], [85°C], >10–5 g/m2/day); transparency visible wavelength (>90 percent); flexibility (curvature <20 mm, reliability: >1 times). A technology9 developed displays multilayers. deposition conducted low (<80°C) plasma damage performance, residual thin controlled crack causes failure during panel-bending must dense pin holes WVTR value. thick enough cover particles generated (CVD), ability multilayers encapsulation. Moresco tool (Model: MAT-001) measures data analyzes total amount passing spectrometer 7a). optimized ∼15 µm, 90 (430–700 nm), ∼5 10–5g/m2/day (WVTR 85 RH, temperature: 85°C) 500 hours. (CVD/atomic [ALD], IJP, printing), (inorganic: SiON, SiO2, Al2O3; organic: IJP—acrylic, epoxy-based resin), continuously. Water (WVTR) measurement barrier (a) (Moresco, Model: MAT-001), (b) (TFE), (c) TFE. With respect reliability, hinders smaller radii (<20 Thus, (∼<20 µm inorganic/organic/inorganic). Once developed—including (8K TV)—then we measure different radii. Additionally, dielectric constant critical touch sensitivity (signal-to-noise ratio) added main fabricating reliability. fabricate display, used. During substrate sensitive may fail result propagation area radius becomes smaller. cracks resulting (especially tensile stress) fabrication B/P, OLED, encapsulation, assembly. As 8 shows, active pad areas cause failure, open issue pan-out continuous Here again, failures primarily occur generate propagate, defects areas. mode degrades panel's lifetime. stress, it strain calculation Young's modulus, pressure-sensitive adhesive (PSA) film, coated significantly. Crack Strain radius.10 ratability (>1 times less mm), structure/advanced (including materials) 8b). coplanar materials, technology) natural minimizes concentration. One would develop innovative great reduced investment cost, decreased operation increase productivity.11 Even celebrate developments possibilities noteworthy Specifically, Therefore, radius, emission, metal shape area, optimized. Development circular polarizer underway. being use along panel/camera/IoT/healthcare innovation mechanical conventional TV—combined healthcare iCloud—will our daily lives into continues evolve, application market. authors like thank collaborators CSOT providing backplanes We acknowledge funding received from Guangzhou City Innovation Project (202009020006) continuing R&D activity Jueng Gil (James) Lee deputy chief engineer Guangdong Juhua Printed Display Technology Corporate Research. He responsible OLED/QLED applications PhD science Tohoku University Japan. reached [email protected]. Zhuo Gao manager Technology. focuses technologies. MS engineering Electronic Science China 2011. Dong Fu CEO vice president physical electronics 1994. Xiaolin Yan officer Group CSOT. leads TCL, SID fellow, serves roles international associations conferences. Institute Plasma Physics Chinese Academy Science.