By C. Perera, JadeTimes News
At first glance, it resembles a relic from the 1980s a small computer screen with flickering, low resolution text scrolling across it. However, this could represent the future. This screen utilizes perovskite light emitting diode technology, which is fundamentally different from the LED technology in current smartphone displays. PeLEDs could lead to thinner, cheaper devices with longer battery life.
Moreover, PeLEDs can both absorb and emit light, enabling integration of touch, fingerprint, and ambient light sensing capabilities into the same material, says Feng Gao of Linköping University in Sweden. "This is difficult but we think it’s possible," he adds.
Today’s smartphones use separate electronic components for such functions. In a paper published in April, Prof. Gao and his team demonstrated a prototype with touch and ambient light sensitivity. "It’s a very nice demonstration. it’s very new," notes Daniele Braga of Fluxim, although he cautions that optimizing these functions could delay commercialization.
Prof. Gao showcased the latest version via video call, with the screen's pixel density nearly doubled to 90 ppi, displaying a simple animation of stick figures fighting. A detailed paper on this prototype has just been published.
Perovskite, a mineral discovered in the 1800s, contains calcium, titanium, and oxygen arranged in a crystal structure. Modern perovskites can be made from different elements or molecules, making them efficient at conducting electricity or emitting light. "By slightly tuning the chemical composition you can cover the full visible spectrum," explains Dr. Braga, highlighting the simplicity and cost effectiveness of mass production.
However, PeLEDs are unstable, degrading with exposure to moisture or oxygen. Loreta Muscarella of VU Amsterdam is developing new kinds of PeLEDs to address this issue. Traditional LEDs last 50,000 hours or more, whereas PeLEDs currently last hundreds to thousands of hours.
There is potential for a different perovskite based technology to enter the market first, photo luminescent perovskites. Unlike LEDs, these materials absorb and re emit light, serving as efficient color filters in TV screens, which could greatly increase brightness and efficiency. Helio, a British company, is working on this technology.
Prof. Gao’s team is focusing on electroluminescent perovskites, which emit light without needing color filters. Although these are sensitive to electrical fields and less stable, they could eventually be more efficient for smartphone, tablet, and TV screens.
Switching to PeLED technology could lower device costs and energy consumption. While exact energy savings compared to OLED screens are uncertain, lab experiments suggest PeLEDs are competitive and may eventually surpass OLEDs in efficiency.
A key challenge is directing PeLED light emission forward, crucial for display technology. Researchers are exploring various techniques, including imprinting nanoscale patterns on PeLED surfaces to improve light emission.
For Prof. Gao, the unique capabilities of PeLED screens extend beyond light emission to functions like fingerprint verification and heart rate sensing. "This is not possible with other LED technologies," he enthuses.