Reflecting on displays

20 February 2018

Author: Peiman Hosseini


Peiman Hosseini operates tools used to manufacture next generation displays.

Electronically displayed information is everywhere; smartphones, laptops, TV, advertising billboards, wearables… the list of devices we use goes on and on. These displays are mostly based on either liquid crystal (LCD) or organic light-emitting diode (OLED) technology. These are great technologies, but they are not without limitations. We have all experienced the poor readability of a phone screen in sunlight and short battery life, largely due to the high power consumption of the display. Recent research has also shown that evening use of these light-emitting devices can negatively affect sleep and next-morning alertness.

So how can we design the next generation of displays to address these issues? A promising approach is to develop displays which can reflect natural ambient light or room lights to illuminate the screen, rather than using the powerful backlighting used in LCDs. Deployed in eReader devices, reflective displays provide vastly improved power consumption and outdoor readability. But this current form of reflective display technology cannot render good colour, nor deliver video refresh rates – a major limiting factor to wider application.

At Oxford University a few years ago, Prof Harish Bhaskaran and I discovered that ultrathin films containing a layer of phase change material could provide an entirely new means of generating vividly coloured reflections from a surface. The bright colour observed was rapidly switchable to another strikingly different colour state, and these states were bistable, meaning they consumed no energy once the change was made.

We published this breakthrough in Nature in 2014 and then co-founded Bodle Technologies a year later, to start work on commercialising the technology. It is now known as solid-state reflective displays, or SRD®.

A Bodle technologies SRD lies on grass. It is a black square with three rows of colours in the middle. Each row is split into two colours: red and orange, green and pale yellow, blue and lilac.

To use this new electro-optic effect as the basis for a reflective display, there are two key challenges for our company. Firstly, we have to develop the routine switching of pixel sized areas of our films to create different colours. Secondly, we must incorporate the control electronics that underpin modern display devices. This is no mean feat, but with the great team we have assembled, we continue to make good progress towards our first, full-sized demonstrators. We are fortunate to be backed by a group of investors that can see the potential of our technology in this large multibillion-dollar global industry. The Royal Academy of Engineering has also provided me with a lot of personal support through my membership of their Enterprise Hub.

The materials and methods we use to make our devices are compatible with processes currently used by existing technologies, and they are suitable for applying to flexible substrates. With a total thickness of the optical layers of approximately 500nm, there is also the potential for fully flexible devices in the future.

Static, non-digital ‘reflective displays’ are all around us – in the form of permanently printed text and graphics. Longer-term, we believe that in an increasingly connected world driven by data, there will be more and more sharing of information via electronic displays, wherever we demand human interaction and intervention. Our thin-film technology offers the chance to eventually seamlessly integrate displays onto the surfaces and objects around us. We believe that one day SRD® will offer us the chance to ‘display anywhere’, rather than be limited by the discrete, rigid displays we currently use.

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Co-Founder and Chief Technology Officer, Bodle

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