Flexible mobile displays: Interview from the research lab with Michael G. Helander

Now that manufacturers have mastered the traditional characteristics of mobile displays like resolution and brightness, it's time for something more revolutionary. We already have HD 1080p and 3D displays on smartphones, as well as handset screens with 1000+ nits of brightness, so what else can we look forward to? Why, our beloved flexible OLED displays, of course. 

Considered somewhat of a milestone towards the dreamy concept videos of flexible, bendable phones and tablets you have seen by TAT, Nokia, Microsoft or Samsung, the flexible OLED tech is behind many research projects.

Recently the Organic Optoelectronics Research Group at the Department of Materials Science & Engineering, University of Toronto, announced their discovery of what is deemed the most efficient flexible OLED display thanks to the use of tantalum oxide coating and other enhancements, as pictured on the right. “This discovery unlocks the full potential of OLEDs, leading the way to energy-efficient, flexible and impact-resistant displays,” claims Professor Lu, the project supervisor.

Michael G. Helander, a PhD Candidate and Vanier Canada Graduate Scholar from the team responsible, kindly agreed to sit an interview with PhoneArena, and give some inside scoop to our readers about what we can practically expect from the flexible OLED technology, and how long it will take for such mobile displays to become mainstream:

PhoneArena: Michael, first we thank you for willing to do this. Dreams about taking a smartphone out of your pocket and unfolding it to reveal a generous screen size are probably still far-fetched since other components are rigid, but what other practical use will flexible OLEDs bring? Are we about to experience the end of cracked mobile displays? How about twisting and scratching screens with plastic substrates?

Michael:One of the big advantages of moving to flexible plastic substrates is not the flexible form factor, but rather that the displays can be made physically thinner. Currently, one of the bulkiest parts of a mobile display is the glass substrate itself. Note that the glass substrate the display is built on is different than the front glass on our cellphones. Typically, the display is fabricated separately and then glued to the front glass plate. The glass used to fabricate the display has to be thick enough to structurally support the display without cracking. Below a critical thickness the glass is just far too fragile to be effective, particularly with the ever-increasing size of mobile displays. The trick is to fabricate the AMOLED display on thin flexible plastic, and then laminate it to the front glass plate of the mobile device, typically made of Corning’s Gorilla Glass.

PhoneArena: Samsung's flexible AMOLED displays are also based on plastic substrates, and the company said we are to expect products with them next year. Do you think that your new tantalum oxide coating and other enhancements bring efficiency that is superior to its technology or to the other flexible OLED tech?
   

Michael: Our flexible devices are at least several times more efficient than the current technology in flexible AMOLED displays. Typically, the technology used in consumer products will be 1-2 generations behind the technology currently being developed in the lab. It usually takes a few years to adapt technologies in the the lab to mass scale production. I would not be at all surprised if Samsung had similar technology already under development at lab scale.

PhoneArena: What is the brightness level we can expect from flexible OLED displays? OLEDs are traditionally less bright than LCD screens, but with suitable anti-reflective coating sunlight visibility remains decent, will that change with flexible OLEDs? How about resolution, will we ever see HD 720p flexible OLEDs?

Michael:I would expect the brightness and resolution of the first flexible OLEDs to be similar to current rigid AMOLED displays since the base technology is the same. A lot of the issues with brightness and resolution of AMOLEDs come down to cost competitiveness. While technologically possible to achieve bright high resolution AMOLED displays, the cost for mass scale production is still prohibitively high. However, with the rapid development in new materials and manufacturing techniques I would not be at all surprised to see a steady increase in brightness and resolution over the next few years. High-brightness HD 720p flexible OLEDs are definitely possible, and even HD 1080p flexible OLEDs should not be that far off.

PhoneArena: Are technologies like DuPont's or GE's OLED printing poised to produce flexible OLEDs for mobile devices on a mass scale and on the cheap thanks to the plastic substrate?
   
Michael:Although printing of OLED displays has been demonstrated at the lab scale level, the difficulty is still in scaling the technology. To be economical, mass scale production requires extremely large substrate sizes on the order of meters wide by hundreds of meters long. The real challenge for printing technologies is achieving uniform film thicknesses for all the different layers in the OLED across such large substrates. Tolerances for the thickness of each organic layer are typically in the range of only several nanometers.

PhoneArena: Finally, what do you think will be the timeframe for your bendable OLEDs to become mainstream and what is your personal wildest dream about the future characteristics of gadgets with them? Do you think concept videos with flexible displays like the ones from Samsung or TAT can become reality one day?

Michael:With Samsung slated to begin production of AMOLEDs on plastic next year, I think 3-5 years is a realistic timeframe for flexible OLEDs to become cost-effective and mainstream; let’s hope that the development of flexible components can keep up! I think that with the advent of printed electronics and other flexible technologies, many of the concepts being floated around are definitely possible, at least in terms of the display. I would love to see flexible and paper thin tablets and cellphones. Although advanced AMOLED displays are poised to reach such a target it will really be the rest of the electronic components (e.g., processor, flash memory, etc) that will be the Achilles heel to such exciting form factors.

PhoneArena: Thank you for the interview, Mike, and we wish you and the team more breakthroughs in advancing the OLED technology!

We'll just add that yesterday we wrote about Korean researchers coming up with a flexible RAM module, and we've also written about two prototypes of flexible batteries already, so there is progress in bending the rigid componentry of our smartphones and tablets, too.

We bet you loved Michael's comment about flexible HD 1080p OLEDs that might be coming down the pipe one day, but loathe the fact that we are still a couple of years away from mass adoption. Let us know in the comments what other feelings you have about the advent of flexible OLEDs, and the ways they can make our interaction with mobile devices even more exciting.

All photos courtesy and copyright of the University of Toronto.