Kateeva, a developer of inkjet deposition equipment solutions for OLED display manufacturing, today formally introduced a suite of YIELDjet inkjet equipment for red, green and blue (RGB) pixel deposition to enable the development and pilot production of large-size OLED displays, including televisions (TVs). The new YIELDjet family, which consists of the EXPLORE and EXPLORE PRO systems, provides display manufacturers with an industry-proven inkjet deposition platform to help bring the next generation of OLED TVs and other large-size displays to market. This year so far, Kateeva has shipped four systems from the EXPLORE family. The company expects to ship three additional systems by the second quarter of 2018.

The EXPLORE family broadens Kateeva’s product line and deepens the company’s penetration of the OLED display sector. The YIELDjet FLEX system already leads the inkjet deposition market for OLED mobile displays, with multiple systems deployed in mass production for OLED thin film encapsulation (TFE). The YIELDjet EXPLORE and EXPLORE PRO tools contain the same demonstrated core technologies found in the YIELDjet platform, with system designs that are optimized for rapid development of RGB pixel printing. Both tools, for instance, feature Kateeva’s unique nitrogen printing capability, which provides an oxygen- and- moisture-free enclosure for inkjet deposition. This capability is known to greatly increase OLED device lifetime.

The new products aim to help customers compress their in-house development- to- pilot-production cycle for printed RGB OLED displays, including TVs. To achieve this, the systems are designed for flexibility and scalability. The EXPLORE processes small panels (up to 200 mm square) for initial development, while the EXPLORE PRO targets mid-size panels (up to 55-in. display) for development through pilot production. As many as nine inks can be loaded into each tool at the same time. This enables accelerated evaluation of multiple materials during critical phases of process development.

The products offer an alternative to the traditional RGB pixel deposition approach of vacuum thermal evaporation (VTE) with a fine metal mask (FMM). Instead, printing is used to form the active layers within the pixels that generate the red, green and blue light emitted from the OLED device. Manufacturers are interested in using inkjet printing to overcome the scalability limitations of VTE with FMM.

VTE with FMM is currently used for small displays to fabricate patterned RGB active layers. However, the approach has not been successfully scaled to enable production of large displays such as those required for premium TVs. White OLED (WOLED) TV works around the issue by using VTE to form an un-patterned white OLED layer. This eliminates the need for FMM and creates the red, green, and blue light using three separate color filters (similar to the structure of a liquid crystal display). Although WOLED TVs are considered the best on the market, RGB OLED TVs fabricated using inkjet deposition can potentially offer superior performance. Moreover, manufacturing costs could be 20 percent lower, according to a recent analysis.

The potential of inkjet-fabricated RGB OLED TVs, coupled with the enabling capabilities of the YIELDjet EXPLORE products, have generated excitement among OLED display manufacturers, according to Kateeva’s President and COO, Dr. Conor Madigan. “There is increasing enthusiasm among our customers to develop RGB OLED TVs and we believe our new systems will help them accelerate their initiatives,” he said. “These companies are innovating rapidly and pioneering novel processes to mass-produce differentiated displays. Our products let them utilize Kateeva’s unique technologies as part of their inkjet RGB pixel printing programs. We are excited to work with them to move this approach closer to mass production.”

The YIELDjet Inkjet Advantage

Kateeva’s inkjet solution for RGB pixel deposition R&D utilizes core disruptive features found in the company’s YIELDjet platform. This OLED production equipment solution has already helped display manufacturers transition to flexible OLED mass production with high yields and low costs. Now, the same features, coupled with additional innovations for RGB pixel printing, promise to enable a similar transition to RGB OLED TV mass production by addressing customers’ yield and productivity priorities. Key YIELDjet technical features and advantages include:

• Pure process environment: Trace amounts of oxygen and moisture, as well as large particles, can degrade OLED device performance and reduce yield. The same impurities are known to degrade OLED device lifetime. Processing in a clean, high-purity environment, therefore, is a central requirement for OLED front-plane manufacturing equipment. The YIELDjet solution features a specially designed nitrogen-purged enclosure that delivers an ultra-pure printing environment and enables fast recovery after maintenance. The result is longer OLED lifetime, higher yields, and higher uptime.

• Superior uniformity: Non-uniform deposition of the printed layer can create “mura”. Mura, which refers to visibly noticeable non-uniformities in the finished display, will reduce yield. Print non-uniformity can be caused by inherent variations in the nozzles contained in the print array. The YIELDjet platform addresses the issue by combining two proprietary technologies—ultra-fast print head monitoring and Smart Mixing™ software. A remote drop inspection (RDI) system measures the drop characteristics for every nozzle in the print array on a continuous basis so that the state of the print array is known at all times. The nozzle data is used to calibrate the proprietary Smart Mixing software, which determines the optimized nozzle mixing for each sub-pixel during the print. The result is a system that delivers displays that are free of print mura in mass production.

• High resolution: To achieve the resolution required for a product like an 8K TV, a key printing imperative is ink drop placement accuracy. This requires high stage accuracy. To enable high stage accuracy for all glass sizes, Kateeva pioneered the use of a “floating stage” for inkjet printers. With this capability, the glass floats on a thin cushion of nitrogen, which flows from a specially designed stationary stage. As the glass is scanned at high speed over the nitrogen cushion, proprietary stage-error correction technology is deployed to ensure the high accuracies needed for RGB pixel printing.

In addition to RGB pixel printing, the EXPLORE tools can be configured to process OLED TFE. This allows customers who are interested in both applications to conduct R&D or pilot production with the same EXPLORE or EXPLORE PRO tool.