October 10, 2011 — Several speakers at the recent OLEDs World Summit 2011 (9/26-28 in San Francisco) discussed the appeal of organic light emitting diodes (OLEDs) for large-format image displays, rising in appeal over liquid-crystal displays (LCD).
James Lee, research fellow at LG Display, made the case for using soluble technology for OLED fabrication, a technology the company has been developing. Though there are remaining challenges that have to be addressed, e.g., soluble material performance, particularly for blue CIE Y, Lee noted that substantial cost reductions can be achieved using this technology because of the simple OLED device structure and the simple bill of materials (BOM) associated with OLED displays (OLED displays require no backlight, just one sheet polarizer, and no C/F) and the simple mura-free process LG Display is developing with a printing partner. The company is confident its printing partner will solve the mura-free printing challenge within the next two years. Still-to-be-addressed system requirements include low power consumption (compensation circuitry), continued cost reduction for competitiveness (e.g., going from FMM to FMM-free patterning technology) and design differentiation (e.g., face-seal encapsulation).
According to Lee, 2012 is the first year that OLED TVs will penetrate the premium TV market. LG sees the market share of LED TVs increasing dramatically from 32% to 93% as the price premium narrows down to 20% from 53% in three years. Volume production of OLED TVs is expected to occur in 2013. "The OLED TV market will start to grow substantially in 2015 once the price premium will be reached at 50% like LED TVs," said Lee.
John Richard, VP, DuPont Displays, spoke about the appeal of OLEDs for large-format image displays. They offer visually compelling images with high contrast, large color gamut and rapid response time, he explained. There are also equipment cost and design advantages because of their very thin format, improved power efficiency, and simple panel structure.
However, he noted that three barriers must be overcome to successfully produce OLED TV:
- Material performance has to meet the thresholds for TV,
- OLED material deposition waste must be significantly reduced, and
- OLED material application equipment must scale to the size and productivity of its LCD counterparts.
Continuing the discussion about using solution OLED fabrication, Richard detailed the key materials challenges that are holding up progress:
- Being able to coat the blanket layers,
- Being able to contain the printing inks in the active subpixel area,
- Keeping successive layers from mixing with each other,
- Being able to clean the coated materials before encapsulation/bonding,
- Being able to print at high speed without visual defects, and
- Keeping atmospheric conditions during printing/coating from degrading the organic materials.
To tackle the challenges, DuPont teamed up with Dainippon Screen (DNS) to address nozzle printing for solution OLED patterning. In 2008, the collaboration resulted in a Gen 4 production-scale printer installed for 730mm