Smartphones, one of the most revolutionary inventions of the 21st century, combined with display technology, have fundamentally changed our lives. Display technology has evolved beyond the early CRTs and LCDs to OLEDs, which offer brighter, sharper screens and play an important role in a wide range of devices, including smartphones. There’s a lot of excitement about what’s next for OLED, and what the future holds for display technology.
What are the most brilliant inventions of the 21st century? The smartphone, the computer in the palm of your hand and the key to ubiquity, deserves the honor. You can’t go anywhere without seeing someone looking at their smartphone. Since Steve Jobs introduced the iPhone to the world, the world’s leading companies have invested astronomically in the smartphone market to create a unique ecosystem. With high-performance cameras, CPUs, and large amounts of memory, smartphones have replaced many portable electronic devices with their overwhelming specifications.
The evolution of smartphones is not just limited to hardware. The convergence with software has greatly expanded the user experience, and with the emergence of various applications and services, smartphones have become an ecosystem in their own right. This fundamentally changed the way people live, ushering in a new era of access to information and communication anytime, anywhere.
At the same time, with the widespread availability of wireless internet and increased awareness, people began to create their own content on their smartphones, ushering in the era of personal media. Many people began to watch articles and videos on their smartphones. The smartphone’s screen for displaying text and video has become increasingly important, and the market has seen a fierce competition for display excellence in response to consumer demands.
The smartphone display race has led to brighter, sharper, more colorful, and more accurate displays. When improving existing displays wasn’t enough, people started to create new types of displays. After much research, OLEDs (Organic Light Emitting Diodes) have become the new mainstream, and they are very different from other displays.
The first and only display technology was a CRT, also known as a cathode ray tube. That’s the screen on the old, pot-bellied televisions your parents’ generation watched. They utilized electrons from an electron gun that hit a panel to produce light, and because of their construction, all devices with CRTs were heavy and thick. Liquid crystal displays (LCDs) were developed in the early 20th century and by the end of the century were portable enough to be used in electronics, solving all of the problems that CRTs had. LCDs led to larger and slimmer screens, and the brown tube was consigned to the dustbin of history.
LCDs consist of a backlight panel that produces light and liquid crystals that display colors. The light from the backlight panel passes through the liquid crystals, which have a kind of polarization structure, and then through a polarizer plate on the front to produce the final output. The smallest unit of display, the pixel, is made up of three elements: red, green, and blue, and the degree of polarization of each element determines the contrast and color. Technologically easy and simple, LCDs improved day by day and dominated the display market for a while. Plasma Display Panels (PDPs) came along to take on LCDs, but the efficiency and low power consumption of LCDs meant that PDPs never saw the light of day.
However, the backlighting of LCDs, for all its many advantages, had a fatal flaw. LCDs, which obscured the light from the backlit panel, had a smaller light output than displays that emitted light. Because of this structural feature, the screen was often difficult to see in strong sunlight. Since the colors are displayed by blocking out the white light, the color gamut could not be increased beyond a certain level to get the exact colors you want. As smartphones are often used outdoors, the need for a display that is a little brighter, more colorful, and clearer than a natural LCD screen gradually emerged.
Organic light emitting diodes (OLEDs), which emerged in response to this need, solve the structural problems of LCDs. It is a display that emits light directly using the effect of autoluminescence, which is the effect of fluorescent organic compounds that emit light when an electric current is applied to them. Instead of a backlight, OLEDs use three organic materials that emit tri-color wavelengths of red, green, and blue, which allows them to be thinned. OLEDs also allow for flexible displays that can be bent freely. Because OLEDs emit light directly, they have better color reproduction and contrast than LCDs, and they consume very little power.
Thanks to these features, OLEDs are being adopted in a wide range of display devices, including TVs, monitors, and wearable devices, not just smartphones. In particular, the future of OLED is looking even brighter as innovative products such as transparent displays and foldable displays are emerging.
However, OLEDs have one flaw: the famous burn-in phenomenon. The short lifespan of the light-emitting elements, which use organic compounds, means that if the same color is continuously displayed for a long period of time, it will leave a visible afterimage on the display itself. Since smartphones have a home screen, this often happens when you’re surfing the web or watching a video and the app icons on the home screen are visible. Efforts to find new organic compounds to address burn-in are ongoing.
In a competitive display market where many technologies come and go, OLEDs are here to stay for the foreseeable future. But how far can OLEDs go to take us to the next level of technology, and will there ever be a new display that can outperform them? We look forward to the future of light led by OLED.
