How the LED helped create a high

This story is part of The Butterfly Effect, a special Spark series about technological advancements that had a much larger impact than most people anticipated.

LED technology is everywhere from household lighting to television screens to computer and phone displays – and it's revolutionizing film and television production.

In recent years, LED screens – flat-panel displays that use light-emitting diodes as pixels – have taken the place of green screens for location filming on major productions, like The Mandalorian and the Star Trek series Discovery and Strange New Worlds.

"Basically, picture the biggest TV set you've ever seen and then bend it," Kevin McGeagh, the head of virtual production at Toronto's Virtual Production House, told Spark host Nora Young.

"A lot of people are familiar with the image of a green screen or a blue screen, where you have an actor standing in front of a big blank wall. We fill that wall in with a giant TV set, and as the camera moves around, we actually use tracking technology to have the wall update in the same way you would have a video game controller and you can fly around the world."

Traditionally, actors perform their scenes in front of a giant green screen, with the backgrounds and special effects added during the post-production stage. In contrast, the giant LED panels blend into the set and display visual effects in real-time. The wraparound, 360-degree displays can encircle the set.

"It can be an odd experience in that it only really looks correct through the camera. And when you see it from outside of it, sometimes things seem a little bit distorted," said McGeagh.

But he says there are benefits to having those visuals playing alongside the actors.

"When you shoot with the screen, the nice thing is you're lighting the subject matter with it. They're very engaged with it... And as things are moving, it feels like they're married together," said McGeagh.

However, adapting to the technology has been gradual, he says, including accounting for things, like the light the screens themselves emit and the flickering that may happen when filming a TV screen.

"I think like a lot of pieces of technology, once people know that it's available and it's been proven, they become a little more willing to dip that toe… We've been talking about this as a dream technology for quite a while. Those types of productions really made people look at it and go, 'Ha, maybe I don't have the money that say [The] Mandalorian has, but maybe I can do a few shots that are really important to the story I'm trying to tell.'"

Although traditional LEDs were first observed in 1907, it wasn't until the 1960s that the technology was first made commercially available.

"I think the biggest thing that was holding LEDs back for that period of time was really just a question of materials cost, the affordability, the availability of materials, learning the purification process, what types of impurities in those semiconductor layers would create the results that you want? How can you sustain those results? And also, how can you make them energy efficient?" said Carrie Meadows, managing editor of LEDs Magazine.

The first red LED visible to the human eye wasn't particularly efficient or bright, Meadows said. It was usually used in industrial equipment as blinking lights and other indicators, and it's still used as a replacement for little incandescent bulbs.

As LED technology was perfected with the application of better semiconductor materials, this technology was embraced for its longevity and controllability, says Meadows.

"There are hundreds of apps ... that can help commercial buildings, health care, all kinds of businesses, institutional, such as education, manage their usage of electricity in lighting and their building systems such as HVAC at the same time, and really help to understand that energy usage."

A related technology that is becoming more common in consumer electronics – including film production – are organic light-emitting diodes (OLEDs). Unlike LED LCD screens, which use a backlight to illuminate the pixels, OLEDs produce their own light.

"Each organic LEDs pixel is actually emitting light," says Zheng-Hong Lu, a materials science and engineering professor at the University of Toronto and the Canada Research Chair in organic optoelectronics.

Lu focuses on the development of next-generation OLEDs, specifically flexible screens made with this technology.

For the consumer market, Lu envisions large displays that are lightweight and able to be rolled up and stored. The most notable example of such a technology is a foldable smartphone, like the one introduced in 2019 by Samsung.

Lu says OLEDs also have huge implications in wearable devices for virtual reality.

"If you think about the TV today, you have a 4K TV. But you want the same resolution, but put on your eyeglasses. You can [have] almost like a cinema-quality display right on your eyeglasses," said Lu.

The challenge to mass adoption of this technology, Lu says, is the cost.

"The [industry] is still not mature enough to really make low-cost flexible screens – except for niche applications, like foldable phones. People don't mind paying a premium. Someday we want something flexible, like a lighting source for example, inside automobiles, inside the house, in a large area. So the cost is very sensitive," he said.

But, he says, major tech companies like Apple and Google are working to make this technology more accessible to the consumer market.

Written by Samraweet Yohannes. Produced by Adam Killick.

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