Phase-change display startup achieves primary colors

December 30, 2016 // By Peter Clarke
Bodle Technologies Ltd. (Begbroke, England), a spin out from Oxford University developing a non-volatile display based on thin films of phase-change material, claims it has achieved a key milestone in bringing its Solid-State Reflective Display (SRD) technology to market.

"We have achieved reflective specifications for the three primary colours required for manufacture of the core optoelectronic films in our Solid State Reflective Display technology," said Professor Harish Bhaskaran, founder of Bodle Technologies.

The SRD technology offers two advantages over LCD displays; it is non-volatile and therefore achieves power savings and it is a reflective display meaning it can be read in sunlight.

Bodle materials are based on thin films of Ge2Sb2Te5 (GST) electrically switchable between amorphous and crystalline states. The material is essentially the same as that used on rewritable DVDs where changes in the refractive index of a thin layer of the material is used to denote a one or a zero for the purpose of digital storage. In Bodle's case thicknesses are reduced to the order of 50 to 200nm.

The crystallization of thin GST layer induces a colour change in the entire film, visible when incident white light is reflected back. Source: Nature and Bodle Technologies.

The company claims Bodle displays will offer vivid colour and bright white for e-readers, wearables and other screen-based equipment. Little energy is required to change pixels and non to maintain a static display thereby minimizing power consumption for mobile equipment.

Bodle also points out that the thin-ness of the pixels make SRD fabrication compatible with flexible substrates and they are scalable down to the pixel size of current high-resolution displays.

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