Graphene mechanical pixels for Interferometric Modulator Displays

A graphene interferometric modulator display (GIMOD) was created by teams from SCALE Nanotech (Estonia), Kavli Institute of Nanoscience (the Netherlands) and Graphenea (Spain). Interferometric displays (IMODs) are a technology on the rise for displays that have low power consumption and high performance in bright environments, properties that are well-aligned with the demands of modern portable devices. IMODs made of other materials suffer from low frame rates and limited color gamut, which has hindered their use. Now, graphene IMODs are shown to operate at up to 400 Hz, cover the full visible spectrum with reduced flicker effect. The demonstrated GIMOD prototype has 2500 pixels per inch, equivalent to more than 12K resolution. The current highest ultra-high definition television (UHDTV) resolution in digital television and digital cinematography is 8K.

Image: GIMOD principle of operation – a mechanical pixel for displays

The research that led to this commercially interesting application started from the quest to detect the position of suspended graphene membranes with a laser beam. Subsequently, the researchers realized that they could turn the optical readout mechanism on its head and use the array of graphene “drums” as a GIMOD.

The GIMODs are produced from two layers of graphene that are assembled using Graphenea’s patented semi-dry transfer method. The double-layer graphene (DLG) is then transferred to a substrate that houses the array of holes that forms the basis of GIMOD. This results in an optical cavity with a movable

absorbing membrane made out of DLG and a fixed mirror formed by the underlying silicon surface. The silicon substrate also plays the role of back electrode for electrostatic actuation – controlled deflection of the membrane. The spacing between the membrane and the back electrode gives the color that is reflected back to the observer. Since each pixel is contacted independently, GIMOD can produce a color matrix with resolution that is well above what the eye can discern. The high yield of the graphene growth and transfer processes are key certificates to potential use in real-world, batch-produced products. The first GIMOD prototype attracted attention of the display industry when it was shown at the Mobile World Congress in 2017.

Other than low power consumption and high performance in bright environments, the reflective-type (e-paper) pixel technology has the favorable property that it reduces motion sickness in virtual/augmented reality applications. The paper describing the GIMOD was published in Nature Communications.

About Graphenea

Graphenea, a technology company founded in 2010, is one of the main producers of graphene. Graphenea supplies CVD graphene and Graphene Oxide to more than 800 customers worldwide. The company is based in San Sebastian, Spain and Boston, USA. In 2013 the company received an investment from Repsol to boost its technological capacity, support its growth as a business and enable it to maintain its international lead within the emerging graphene production sector.

Graphenea, which employs 25 people and exports graphene materials to 60 countries, supplies its products to global operations for universities, research centers and industries. Graphenea also produces Graphene Field-Effect Transistor chips (GFETs) and a Graphene Foundry service.

Graphenea is a partner of the Graphene Flagship. The EU launched this 10-year investment push research programme that aims to find ways of commercializing graphene.