Paper 2.0: From flexible screens to smart solar cells

Sir Richard Friend, the Cambridge University physics professor who has just completed a lecture tour of New Zealand, recently stacked all 78 volumes of the 2005 editions of Physical Review on the floor of his office.

Sir Richard Friend

“I probably broke all sorts of OSH rules,” says Sir Richard, whose towering wall of paper comprised 80,000 pages of journal papers submitted to the physics journal in that one year period. In 1962 the journal, which accounts for a decent chunk of the new peer-reviewed literature published each year in the field of physics, filled six volumes – 6,000 pages.

Sir Richard’s point – the published output of the science world has increased voluminously in the past few decades. The problem, as he sees it, is that most of it is crap.

“The scientific literature is an absolute minefield. Most of it is rubbish, worse it is boring.”

Not surprising then, that Sir Richard has set out in his career to discover things for himself, through trials and experiments that have resulted in dozens of patents,  at least three spin-off companies and successful partnerships with major consumer electronics makers.

The two golden eras of Cambridge, says Sir Richard, where the late 1600s when Sir Isaac Newton was carrying out his experiments in optics and gravitation and the 1920s when Sir Ernest Rutherford undertook several pioneering nuclear physics experiments. Sir Richard is the Cavendish Professor of Physics, a position once occupied by Sir Ernest, so he feels a connection to the famous New Zealander. Sir Alan MacDiarmid, another Nobel-winning New Zealand scientist, mentored Sir Richard and his team who were the first to make a polymer light-emitting diode.

Since that development in 1989, Sir Richard’s team has expanded on its work on polymer light emitting diodes and molecular semiconductors, developing technology used in consumer electronics through to solar power cells.

PLED screens

The 1989 discovery at the Cavendish Laboratory led to the founding of Cambridge Display Technology in 1992, a company set up to commercialise polymer light emitting diode technology. What are the advantages of P-OLED over more conventional LCD screens? According to Cambridge Display Technology:

Because P-OLEDs emit their own light, they are brighter, clearer, and have a virtually unlimited viewing angle. Their high contrast and wide dynamic brightness capabilities make them a better solution for night-time and daylight use. P-OLEDs also have a very fast image refresh rate that is maintained at low temperature, and are ideal for full colour video in TV, internet devices, PDAs and other ‘smart’ personal display products. Because P-OLEDs do not require a power-hungry backlight, they are energy efficient and are thinner and lighter weight.

Hence, CDT’s partnering with electronics companies like Phillips and Seiko-Epson. Now, OLED screens are starting to make their mark in the tech space as they become the screens of choice for smart phones and a new generation of TV sets. Video walls are the next step, with the technology underpinning prototypes for virtual wallpaper that can change colour and display images and video. CDT was bought by Japanese chemical company Sumimoto in 2007.

Flexible displays

Plastic Logic’s flexible screen

After pioneering ways to develop higher quality displays at competitive prices, Sir Richard turned his attention to developing screens that can flex. This is often seen as the successor technology to the current range of rigid tablets and smart phones on the market. The ability to roll up your phone or tablet is an attractive proposition.

“Why isn’t it in the shops? The investors might ask that too,” says Sir Richard who founded the company Plastic Logic to commercialise flexible screen technology.

“It’s taken a long time to get the yield up. But it is a market-ready technology.”

Plastic Logic specialises in producing flexible, ultra-thin plastic displays. What can they be used for? Initially, Plastic Logic wanted to get in on the ebook and tablet revolution, creating flexible versions of these types of devices – sort of like a Kindle that you can roll up. The displays were hot drawcards at trade shows around the world, but as this article points out, Plastic Logic had to rein in its ambitions somewhat as the market hasn’t developed as quickly as it expected.

When I asked Sir Richard last night when a mass market flexi-screen smart phone or tablet is likely to be on the market, he prevaricated. “It depends what the use is for,” he said taking my paper notebook and illustrating the problems that are presented to electronic circuits and display surfaces when you fold them into anything other than right-angles.

So the roll-up screen revolution is still a while away. In the meantime, Plastic Logic has shifted its focus to licensing technology to big electronics makers, much as CDT did from the start. But Plastic Logic has invested in a major factory in Dresden, Germany, which can churn out hundreds of thousands of screens each year.

Organic solar cells

The work on PLEDs, organic semiconductors and printing electronics onto thin sheets of flexible plastic led on quite logically to work in solar cell technology.

Pay-as-you-go solar

“Solar is not yet cost-effective,” says Sir Richard. That’s a symptom of the fact that solar cells are, by and large, still based on silicon, which is expensive to process as a hard sheet or wafer. The organic polymers get around that because they can be printed onto thin, flexible films.

“The great selling point is we don’t have to follow the rule book of silicon. The downside is we don’t get to follow the rule book of silicon.”

Recently, Sir Richard’s team also unveiled development of new hybrid solar cells that capture more of the sun’s light spectrum to boost the efficiency of the cells for energy production.

Thin, flexible solar cells effectively mean we  can move away from the bulking solar panels currently used to capture the sun’s energy for humankind’s use. Windows or the surface of buildings could be generating energy.

“Lots of people think its a smart thing to do,” admits Sir Richard. “The problem is the building industry is very conservative. They are worried about discoloration, what it will look like in 25 years. It’s still an unproven technology”.

The solar cell development has been spun off into yet another company – Eigth19.

“By the way, I’ve still got a day job in the university,” quips Sir Richard.

One Eight19 project is aimed at the millions of Africans who still rely on kerosene lamps to light their homes after dark. The Battery Box draws current during the day from a flexible solar cell panel so that it is fully charged by nightfall to supply LED lighting – and charge the odd cellphone or two. There are some 750 million “off-grid” cellphones in use in the developing world, so there’s a large market to tap.

The Battery Box also has a novel business model. Rather than asking low income households to pay the cost of the box upfront, users pay as they go – receiving a text message on their phone with a code to activate the box, making micro-payments as they go.

“It looks as though this might fly,” says Sir Richard.

“Its been trialled extensively in Kenya. Cheap light enables school kids to get more education.”

Sir Richard Friend toured New Zealand as the the Royal Society of New Zealand’s 2012 Distinguished Speaker. This Listener piece has more on the science behind his innovations.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s