TECH SPECIAL................... IT'S ALL ABOUT DISPLAY

TECH SPECIAL IT'S ALL ABOUT DISPLAY





G Rajeswaran and IIT-Madras are working on an R&D project to make OLED screens at low cost in India. Hari Pulakkat writes about why displays are an active area of research around the world as new materials promise extraordinarily large and clear colour displays and improving flexibility

As the leader of the team that developed Organic Light Emitting Diodes (OLED) in Eastman Kodak, G Rajeswaran knows a bit about this emerging technology . He is setting up a company in the US for manufacturing LED flat panels. In India, he has a slightly different objective: bring in a disruptive technology to kickstart domestic manufacturing in OLEDs.The Indian Institute of Technology in Madras is partnering him.

Rajeswaran and IIT Madras are developing the initial ideas for an R&D project to manufacture OLED screens at low cost in the country. If approved and funded by the government, this Rs 50-crore project could develop the processes necessary for an entrepreneur to set up manufacturing facilities at less than Rs 100 crore. “We are looking at ideas that can make India the centre of a disruptive display manufacturing industry,“ says Rajeswaran.

Currently, no one in India manufactures electronic displays though the domestic R&D is slowly expanding.Samtel was once a large manufacturer of Cathode Ray Tubes (CRT) for colour television. It had to close down its CRT division in 2008, as Liquid Crystal Displays (LCD) began their onslaught on conventional picture tubes, but the company's legacy lives on at the Indian Institute of Technology (IIT) in Kanpur. Samtel funded research in display technologies there, which now thrives as an IIT Kanpur unit. Its implicit mandate: raise the level of domestic technology in electronic displays.

Displays are an active area of research around the world as new materials promise extraordinarily large and clear colour displays. Scientists expect to develop foldable screens, that can be rolled into a pen-sized device, e-paper on which you can write and so on.Imagine a mobile phone that can be folded into your pocket, or a screen that can be expanded to play a video on your phone. What if your touch-screen touched you back?
Although scientists visualise these destinations, there are also some prob lems to be solved before the world gets to such exotic stuff. “Most low-hanging scientific problems have been addressed,“ says IIT Kanpur professor Deepak Gupta. “But we need to solve difficult technology problems.“ Some of these problems have to do with manufacturing. Others are about making large displays, while still others are about making the displays flexible.Some vital materials for displays are disappearing from the earth too.

In the last decade, LCDs have deeply penetrated and become entrenched in the consumer market. Yet despite their popularity, LCD is considered a poor technology. Liquid crystals can orient themselves in different ways depending on a current, but one thing they cannot do is produce their own light. So every LCD screen requires lighting from behind. They need colour filters too. Finally, about 80% of the energy is lost through light switches and colour filters.

LCDs have other problems such as slow response times and low contrasts. Yet there are advantages. Its manufacturing technology is mature and quite cheap and the technology has penetrated so much that it is now roughly an $80 billion industry. Displacing it is no easy task, but some new generation technologies are developing fast. “New displays for the mass market have to be cheap, robust and efficient,“ says Dubdutta Ray, assistant professor of electrical engineering at IIT Madras.OLED is among the most advanced of LCD competitors.

OLED entered the commercial market about 15 years ago and has taken 15% of the display market so far. OLED is still expensive to manufacture as the scale is not big enough. At IIT Madras, the engineers are trying to lower the barriers through a colour patterning technology that is extremely fast to manufacture, and hence woks at lower costs. It is also trying to replace the glass substrate with silicon substrate.“With a silicon substrate, we can integrate electronics as well to the display,“ says IIT Madras professor G Venkatesh.With the new technique, an entrepreneur can set up manufacturing with investments of less than Rs 100 core.

Even if the IIT-M project is approved soon, it will take a few years before a process is developed that can be transferred to industry. Meanwhile, around the world, OLED technology is advancing rapidly. Screens are becoming thin and large. They are becoming flexible too. LG is already selling an OLED TV with a screen that is only 97 millimeters thick. Samsung sells a mobile phone with an OLED screen bent at the edges.

OLEDs are soft materials. The displays do not need a glass substrate, which removed the restriction of rigidness.“Samsung and LG have mastered the art of making flexible substrates,“ says Rajeswaran. It is not science fiction to imagine that flexibility will be pushed to its limits. OLED lighting could be wrapped around a pillar. Displays can already be folded like a newspaper without loss of image quality .

OLED displays have their competitors too. One of them is quantum dots, inorganic materials that are excellent emit ters of light. Quantum dots provide even better colour purity than OLEDs, but the technology is still not ready for commercial use. They are being used in some LCD displays to enhance colour quality, and might compete directly with OLEDs after a few years.

OLEDs and quantum dots appear set to be the mainstay of future displays for some time. However, scientists are still looking for better emitters of light that can be used in displays. One recent candidate is the mineral perovskite, which has some remarkable properties that makes it useful for solar cells, lighting and displays. However, using them in commercial products is decades away. “It takes 15-20 years for a technology to mature enough for commercial use,“ says B M Arora, visiting professor of electrical engineering at IIT Bombay. It should give OELDs and quantum dots at least a decade of supremacy.

ET23MAY15