Manufacturing Bits: Nov. 11

Plastic smartwatch displays; flexible consortium; GaN microscopy.


Plastic smartwatch displays
LG Display has begun production of what the company claims is the world’s first circular plastic OLED (P-OLED) display.

The P-OLED is the display for the company’s new smartwatch, the LG G Watch R. Based on the Android Wear operating system, the smartwatch is powered by Qualcomm’s 1.2-GHz Snapdragon 400 processor. It also has 4GB of storage and 512MB of RAM.

The P-OLED display, which is perfectly round, is 1.3-inch in diameter and 0.6mm thin. The screen area is 57% larger than that of a square display of the same size. With a 320 x 320 resolution, the display boasts a 100% color gamut, a 300nit peak luminance, and an unlimited contrast ratio. The display also features a power save mode (PSM), which enables the screen to retain the same resolution without a power supply.

Worlds first circular plastic OLED (P-OLED) display (Source: LG Display)

Worlds first circular plastic OLED (P-OLED) display (Source: LG Display)

An organic light emitting diode (OLED) is a flat light emitting technology. Traditional OLEDs are also non-flexible displays. OLEDs are made by placing a series of organic thin films between two conductors. A bright light is emitted when a current is applied. OLEDs do not require a backlight. In addition, OLEDs are sealed to prevent them from exposure and moisture.

In contrast, flexible OLEDs promise to enable a new generation of displays, which are bendable, rollable, foldable and stretchable. LG’s plastic OLEDs go through a similar production process as a traditional OLED. But plastic OLEDs use a plastic substrate and a different sealing material. “First, an organic matter called polyimide (PI) is coated on the lower part of the glass,” according to LG. “Also a specially developed form of multi-layered organic and inorganic film which protects OLED elements is used to encapsulate OLEDs from moisture.”

To enable the P-OLED, LG Display also developed a circular mask. This, in turn, enables organic materials to be deposited simultaneously. The process also improves deposition efficiency, while employing a highly precise laser cutting and processing technology.

Flexible consortium
The German Federal Ministry of Education and Research (BMBF) has launched a new consortium to develop flexible OLEDs.

The €5.9 million project, called the R2D2 consortium, includes Fraunhofer FEP, Audi, Diehl Aerospace, Hella KGaA Hueck, Novaled, Osram and Von Ardenne. The consortium will cover the entire flexible OLED value chain, including material research, plant construction, component technology and application studies for future products.

Flexible OLEDs to enable new apps (Source: Fraunhofer FEP)

Flexible OLEDs to enable new apps (Source: Fraunhofer FEP)

Many companies have established OLED technology on a rigid glass substrate. Flexible and transparent OLED displays could be used in various new applications, such as car windshields, curved displays, lamps and wearables. Flexible OLED modules could be used in aircraft, automobiles, consumer items, among other systems.

“The BMBF-funded project R2D2 investigates production-related processes and technologies for the manufacturing of flexible and shapeable OLEDs. The piecewise manufacturing as well as the roll-to-roll technology approaches will be pursued,” said Christian May from Fraunhofer FEP, on the organization’s Web site. “The advantages and disadvantages of these manufacturing concepts as well as possible synergies shall be identified. Current challenges of the OLED, like durability, efficiency and homogeneity of the luminance will be addressed at the same time.”

GaN microscopy
The Fraunhofer Institute for Laser Technology and RWTH Aachen University have developed a new microscopy technique for analyzing gallium nitride (GaN).

The technique, dubbed near-field microscopy, penetrates the nanometer domain to enable an optical view of GaN, a technology that is used for the production of LEDs, RF chips and other devices.

Using near-field microscopy, researchers obtained an optical 2D image showing tensions in the crystal structure of undoped GaN wafers. Simulations quantified the extent of the tension. The technique was also applied to doped GaN layers.

Near-field microscopy is a non-destructive technique, which has some advantages over current techniques. In some cases, GaN layers are studied using a transmission electron microscope (TEM), but the costs are high and throughputs are slow for this technology, according to researchers. Another technology, mass spectrometry, is used to study the electronic properties of GaN. This technique can damage the sample and is unable to ascertain the concentration of doping atoms at a comparable resolution, according to researchers.

Near-field microscope with a fragment of a gallium nitride wafer. (Source: Fraunhofer, Aachen)

Near-field microscope with a fragment of a gallium nitride wafer.
(Source: Fraunhofer, Aachen)

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