Unwrapping the displays of tomorrow. Christmas is a time for giving the gift of screens – and they are improving every year

Author: David Benady, Technology Writer and Contributor to the SmartKem Website

Electronic devices featuring screen technology are flying off the shelves as Christmas approaches. There’s nothing like unwrapping the latest mobile phone, tablet, smartwatch, laptop, or activity tracker on the big day to really feel the festive thrill. And while some may yearn for Christmases past, there’s no doubt that the screens of today offer greater clarity, brightness, and definition than any gifts of old. We can only wonder at the Christmas yet to come and the captivating technologies that await future generations. This year’s celebrations will be dominated by three classes of screens – LCD, OLED and MiniLED. The New Year will usher in further work on the next leap in screen technology, the microLED.

Let’s unwrap the details of these technologies, and gaze into the future to explore the developments which are yet to unfold.

 

 

LCD

Liquid Crystal Displays (LCD) are the predominant screen technology of our time, accounting for 74% of the display market globally and worth some $122.8bn in 2021, with 90% of TVs, most laptops and feature phones and most tablets using these screens.

LCDs are like a grilled cheese sandwich, there are two sheets of glass (bread), with grill marks (polarizers) and liquid crystal gel in between. The liquid crystal molecules resemble a DNA like structure, a helix, and allow the light to pass through from the bottom glass and out of the front glass; it appears like a bright pixel. When a voltage is applied to this structure, the helix untwists and blocks light so the viewer perceives a dark pixel. By applying a red, green or blue color filter on top of this structure and causing the light to selectively go through some combination of these colors, a display with up to 16 million colors is created.

Crucial to LCD technology is the light source. For most screens, this comes from a backlight, created by a panel of Light Emitting Diodes (LED) which pass light through the liquid crystal sandwich to create images. Those LEDs can be switched on and off, dimmed or brightened by zones, via printed circuits on a substrate. These substrates are usually made of glass or printed circuit boards (PCB) which tend to be rigid, thick, and fragile. SmartKem has been designing backlights using its Organic Thin Film Transistors (OTFT) that sit on a thin sheet of plastic, making your phone or tablet, thinner, lighter, and virtually unbreakable.

 

OLED

Offering superior colour and sharper contrast than LCD, Organic Light Emitting Diode (OLED) screens account for 25% of the global screen market and were worth some $41.6bn in 2021. OLEDs work on a different principle from LCD screens. Instead of using crystals to act as an on/off switch for a backlight, OLED screens emit their own light from a panel of phosphorous materials called emitters. These are patterned on glass as tiny pixels and subpixels and they emit light when a voltage is applied, illuminating the display. Today the high end TV sets are OLED and so are most smartphones, whether Apple or Samsung. Meanwhile, SmartKem’s technology is set to transform OLED displays too as it is ideal for making a lightweight and flexible backplane. The backplane is the layer where transistors are placed to turn on and off the pixels and is positioned behind the phosphorous emitters to form the images.

OLED TVs are much thinner than LCDs because they have no backlight, and the backplane is placed on a sheet of glass. SmartKem’s technology can make the backplane thinner and lighter, allowing for transistors to be printed on a film of plastic. This will dispense with the need for heavy-duty brackets to secure OLED TVs to the wall. OLED TVs made with a flexible backplane can be hung on the wall and in the future rolled up and put away.

 

 

MiniLED

The growth of OLED technology over the past ten years has started seriously eating into the LCD market. LCD makers are looking to strike back at OLED’s superior contrast and sharpness. As light from an OLED can be switched on and off, this creates true, deep black essential for high contrast. But LCDs only partially block their LED backlights in certain areas of the screen, rather than switching them off completely, so the dark areas look grey rather than deep black. The LCD manufacturers have responded to OLED by shrinking down the size of the LED backlights (hence MiniLED) and using more of them. This means the local dimming can be more precise and help create greater contrast, offering what is known as high dynamic range (HDR), offering greater contrast and brightness.

Many TV manufacturers have started launching miniLED backlit screens, so you might watch your favourite Christmas films on one of these if you’ve recently upgraded. Other yuletide gifts are also incorporating them, with some Apple iPads boasting the technology. For instance, the screen of the iPad Pro 12.9 inch uses 10,000 miniLEDs for its backlight – these are 120 times smaller than the previous generation – and has 2,500 dimming zones. This gives a very high contrast ratio, showing the deepest of blacks and nearing the level of definition of an OLED screen. Laptops are also joining the miniLED backlight revolution.

Currently most of these miniLED backlights use Printed Circuit Boards or Glass as the substrate, offering SmartKem the opportunity to replace them with OTFT on film, reducing their footprint, weight, and performance.

 

MicroLED

This technology is aiming to perform better than LCD and OLED and take over the market. It has the low power of LCD, the color and contrast of OLED and while still an emerging technology, holds a lot of promise. Billions of dollars have been invested in recent years to develop this technology.

This technique takes miniLED even further, miniaturising each LED down to the size of a pixel, so each screen has millions of microLEDs, one for each sub-pixel. Samsung and Sony have built large TVs and Signs using LEDs that are tending from mini to micro. These have received rave reviews, but they are priced at several tens of thousands to over a hundred thousand dollars. But all new display technologies start expensive and get cheaper over time.

Making MicroLED displays is non-trivial. The backplane technologies borrowed from LCD and OLED, namely IGZO, LTPS and others are created at very high temperatures – over 300 degrees Centigrade. Here is where SmartKem has a distinct advantage. SmartKem OTFT can be created at 80 degrees Centigrade, thereby offering manufacturers the opportunity of building this layer atop the MicroLED stack without damaging them. This is cost effective and offers design flexibility along with other advantages.

 

However clear and bright the pictures offered by the most popular screens this Christmas – from the latest TV to virtual reality headsets – the quality is only going to improve over coming years. Future generations will benefit from lower costs and more efficient production processes creating screens that are light, effective, and produce images of the highest quality. Roll on Christmases yet to come.