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Let's face it: smartphone screens are getting a little boring. Apart from going closer to the edge of the bezel, it's all just increasingly larger displays in the same rectangular shape, with most attempts to deviate from this form factor failing.

But what if we didn't have to put up with that? What if a radical new way of looking at our smartphone could mean we completely change the way we use our smartphones and tablets? Flexible displays could do just that, and it's a technology that could be worth billions in just over half a decade.

The second you mention flexible displays, most people turn off. They don't see the point in being able to bend your phone - and if that was all that flexible displays allowed, they'd have a point.

But imagine if your smartphone could expand to tablet size, or you could wear a curved display on your wrist. Many people already know that flexible screens can be rolled or even folded, but more importantly they also offer much greater durability.

A study by warranty provider Square Trade suggested that iPhone and Android device owners in the UK spent £1.2 billion on repairs between 2007 and 2012, and the most common cause of damage was accidental drops. While traditional glass touchscreens shatter and scratch, flexible displays can survive similar falls unscathed.

The technology dates back to the 70s, when research company Xerox PARC produced the first flexible e-paper display. Billions of pounds have been sunk into the research and development of flexible displays since then, with limited results. Cambridge-based Plastic Logic showed off a concept newspaper that could be rolled up and put in a bag around seven years ago, but the technology has struggled to get off the ground.

At the same time Polymer Vision, a company spun out of the Philips R&D lab in Eindhoven, tried to release a folding e-ink display, but couldn't get to the economy of scale needed - plus, the company told us, it was hard to convince people that their new device wasn't horrendously brittle.

Thankfully in the last couple of years we've seen a flurry of prototypes heralding the arrival of this technology on the consumer electronics scene, meaning we could get our hands on the new wave of devices in the not-too-distant future.

A recent report from Visiongain suggested "the global flexible display screens market will reach US$260.3 million" this year, but expects it to be the "benchmark technology for mobile devices" by 2018.

An IHS report from early June is also optimistic about the future of flexible displays suggesting that worldwide shipments will climb to "792 million units in 2020, up from 3.2 million in 2013", taking market revenue to around US$41.3 billion, although other reports are more circumspective, suggesting that the market will only be worth $3.2 billion by 2017.

Designing the future

The numbers are still very much up for debate, as we're not even at the product stage yet. However, prototypes for flexible devices already range wildly and the potential is exciting.

At the shallow end, there are displays that simply curve around the edge of a traditional rectangular smartphone, as shown by Samsung.

Manufacturers could design user interfaces to make use of these spaces as distinct touch control areas for navigation, or as secondary displays for specific information. Imagine a permanent battery meter and signal strength display, or a dedicated notifications area that provides at-a-glance information regardless of your activity or the app that you are in, without detracting from your normal smartphone use.

One could easily see a version of Android being brought out to cater for this, using the top, bottom or spine of the phone to deliver notifications.

As the technology improves, smartphone forms will become a great deal more imaginative. Freed from the restrictions of rigidity, we could see a real drive toward designs that fold up to be truly portable, but also allow us to expand our smartphones to large tablet size for watching video.

The trend toward larger displays and hybrid smartphone/tablet devices indicates clear demand in the market already.

Interact in a new way

We could also find new ways to interact. The Nokia Kinetic, on show at Nokia World 2011, allowed users to flex the device in order to control it. You could scroll by twisting, or answer the phone by giving it a squeeze.

It's clever ideas like this that will capture the imagination of the public when a manufacturer delivers the first truly malleable phone - not just the fact that you can wrap it around your finger.

A similar idea has obviously occurred to Apple, as you can see from this patent application which discusses a system to detect "force exerted on a flexible display". A touchscreen that could determine the force you apply and react accordingly would be a great deal more intuitive to use.

It could also have major implications for apps and games. A harder strike on a virtual piano key, for example, could play a louder note - this is already possible, but flexible screens would give the user so much more relevant feedback.

The potential applications in wearable tech are also striking. Flexible displays could serve the burgeoning smartwatch industry, or be used in clothes themselves - imagine a display on your sleeve that bursts into life when you have an incoming call and prompts you to pop your earpiece in.

But we're getting way ahead of ourselves here.

So, what's actually happening now?

All major manufacturers of smartphones are working on flexible displays, in one form or another, for a multitude of devices. Samsung, LG, and Nokia have all shown off prototypes, where Sony, Phillips, Sharp, Toshiba, and others have revealed they're also working on the technology.

Even Apple has already filed patents in this area, showing that the race to release the first smartphone with a flexible display is clearly on - although the early pacesetters look to be LG and Samsung.

Samsung showed off its bendable OLED displays, dubbed Youm, at CES earlier this year, where LG Display followed up with something very similar at the Society for Information Display conference a few months later.

Both prototypes were crafted from thin plastic and based on OLED (organic light-emitting diode) technology - the same kind that's powered the high-performance displays in the Galaxy S2, S3 and S4.

Flexible LCD displays are possible, but OLED is preferable because it doesn't require a backlight. This enables thinner and lighter designs, critical for a bendable screen. OLED also offers deeper black levels, higher contrast ratios, and greater power efficiency.

The e-ink / flexible display combination is the most advanced example of this technology – and you're probably already using it today if you're one of the millions of ebook readers.

The Amazon Kindle, for instance, is packing a flexible display - that's what makes it so robust. However, bringing out a completely flexible ereader on the same scale would be too expensive, and require a flexible case, battery and processor too.

And while e-ink is good for the written word, it's not use in smartphones as it can't handle HD video. It even struggles to reproduce colour to the same degree as a Super AMOLED or LCD display.

The general consensus is summed up in a recent IHS report into the possible state of the flexible display market: "We predict OLEDs will be the leading flexible display technology during every year for the foreseeable future."

Wait - there's a problem

But can a flexible display offer anything approaching the resolution and clarity as seen on the stunning HTC One and Samsung Galaxy S4?

"It's very difficult to have high definition screens that are also bendable and flexible," Professor Andrea Ferrari from Cambridge University told us. That's because of current technology limitations.

LG Display already demonstrated an unbreakable and flexible 5-inch plastic OLED panel for mobile devices that was labelled as HD, but it's unlikely that early flexible displays will match their rigid counterparts when it comes to pixel density.

Raza Ali, IT & Telecom Analyst at Visiongain, added: "The flexible screens in early devices will not be as good as traditional glass OLED initially. However, the quality will get better with time and eventually surpass glass OLEDs."

Making everything else flexible

There's also the issue of the myriad other components needed to enable a bendy phone or tablet. It's fine for the display to flex, but if the battery and other components can't do the same, then how can we ever expect progress here?

That's what makes the recent developments with graphene so exciting. This flexible carbon is extremely strong and could be used to make the display and the rest of the components in a smartphone flexible as well.

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Professor Ferrari told us that graphene is the "strongest and most stretchable material, flexible and bendable, transparent and conductive," going on to explain that "these properties are ideal for interactive displays."

Plastic Logic is already using the material to overcome the barriers to flexible screens, working with the Cambridge Graphene Centre to overcome the inherent issues.

"Plastic Logic is working with new materials which will help make batteries flexible and energy-dense enough to power these flexible display screen devices" according to Ali, explaining that "there will be a whole new submarket working on subsidiary electronic components needed for flexible display devices. There is a lot of research and development going on... to make truly flexible display devices a reality in the near future."

As for the touchscreen, we are used to glass, and plastic simply doesn't have the same feel. Luckily the makers of Gorilla Glass, Corning, are already working on something called Willow Glass which is flexible and (according to Corning) "formulated to perform exceptionally well for electronic components such as touch sensors".

This material will even allow electronics to be printed directly onto the substrate and combined with the glass all in one manufacturing process - another big advantage that OLED technology has, as it can be printed in a variety of ways.

But will anyone be able to afford a flexible phone?

Cost is always a consideration with new technology - OLED TVs are a brilliant idea, but have been hampered for years by eye-watering price tag.

The latest rumours are that the forthcoming Samsung Galaxy Note 3 may be the first mass market device with a flexible display, but the company has yet to announce any firm plans.

So, should I really care about a bendy phone?

Early flexible display devices aren't likely to offer much, or indeed anything, in the way of functionality beyond current smartphones.

What they will offer in the short term is the possibility of lighter and stronger devices in familiar form factors.

It may not be thrilling, but, as Ali explains, "it is a huge leap forward in terms of display technology, especially since conventional glass screens are so prone to cracking even if dropped from a low height."

By comparison flexible displays "would be unbreakable, and would be able to take a huge amount of wear and tear before showing signs of abuse while maintaining a high screen quality and resolution."

As the technology matures over the next couple of years, we'll see some designs that use flexibility to maximise space and offer additional displays and controls.

When manufacturers can make batteries and other components flexible as well, then we will see some really inspiring designs.

It's highly likely in the short term we'll see one of the Asian manufacturers bringing out a standard smartphone with a flexible e-ink display on the back for web and ebook reading, but this will be a niche product to test the market in the same way as the Samsung Galaxy Beam with built-in projector.

But who wouldn't love to have a small, highly portable smartphone that's capable of expanding to full 10-inch tablet size? That will be a device that people will rush out and buy… but there's still time to enjoy the Samsung Galaxy S5 before that comes about