In this blog post, we examine how smartphone and display technology has evolved thus far and explore its potential future trajectory.
What is the most brilliant invention of the 21st century? The smartphone, often called the key to realizing ubiquitous computing—a computer in your hand—is certainly worthy of that honor. No matter where you go, you can easily find people looking at their smartphones. The smartphone has transcended being a simple communication device; it has become a hub of information and the center of daily life. Since Steve Jobs introduced the iPhone to the world, leading global companies have invested astronomical sums to build the unique ecosystem of the smartphone market. Smartphones, equipped with high-performance cameras, powerful CPUs, and large memory capacities, began replacing many portable electronic devices with their overwhelming specs.
The evolution of smartphones wasn’t limited to hardware alone. Through integration with software, it vastly expanded the user experience. With the emergence of diverse applications and services, the smartphone itself became an ecosystem. This fundamentally changed people’s lifestyles, ushering in a new era where information could be accessed and communication could occur anytime, anywhere.
Coinciding with the rapid spread of wireless internet and improved public awareness, people began creating their own content using smartphones, heralding the era of individual media. Many people started consuming the flood of text and video pouring out from smartphones. The smartphone screen displaying this content grew increasingly important. Driven by consumer demand, the market saw fierce competition over display excellence.
Thanks to this smartphone display competition, brighter, sharper, more vibrant, and more accurate displays kept emerging. When improving existing displays proved insufficient, people began creating new display forms. After repeated research, OLED (Organic Light Emitting Diode) emerged as the new dominant technology, showing many differences from other existing displays.
The only display technology in the early days was the CRT, known as the cathode ray tube. That’s the screen in the bulky televisions our parents’ generation watched long ago. It utilized the phenomenon where electrons fired from an electron gun struck the panel to emit light. Due to its structure, devices equipped with CRTs were all heavy and thick. LCD (Liquid Crystal Display), developed in the early 20th century, advanced to a point where it could be implanted into electronics by the end of the century, solving all the problems CRTs had. LCDs led the way in screen enlargement and slim design, and the cathode ray tube faded into the annals of history.
An LCD consists of a backlight panel that emits light and a liquid crystal layer that expresses color. Light emitted by the backlight panel passes through the liquid crystal layer, which has a specific polarization structure, then passes through the front polarizing plate to produce the final output. The smallest display unit, the pixel (Pixel), consists of three sub-elements: Red, Green, and Blue. The degree of polarization of each sub-element determines the brightness and color. Technologically simple and straightforward, LCDs advanced daily and dominated the display market for a long time. PDP (Plasma Display Panel) emerged challenging LCD, but it couldn’t compete due to LCD’s efficiency and low power consumption.
However, LCD’s backlighting had a critical flaw alongside its many advantages. LCDs, which block light from the backlight panel, had relatively low luminance compared to self-emissive displays. This structural characteristic often made screens difficult to see under strong sunlight. Because they express color by blocking white light, their color reproduction accuracy—the ability to accurately display desired colors—could not be raised above a certain level. Given smartphones’ frequent outdoor use, the need for displays that were brighter, more vibrant, and sharper than natural LCD screens gradually emerged.
Organic Light Emitting Diodes (OLED), developed to meet this demand, structurally resolve the issues inherent in LCDs. They are self-emissive displays that directly produce light using the electroluminescence effect—where fluorescent organic compounds emit light when an electric current is applied. OLED enables thin-film fabrication because it uses three types of organic materials emitting the primary color wavelengths of Red, Green, and Blue instead of a backlight. Furthermore, OLED allows for the creation of freely bendable flexible displays. Since OLED directly emits light, it offers superior color reproduction and contrast ratio compared to LCD, along with significantly lower power consumption.
Thanks to these characteristics, OLED is being adopted not only in smartphones but also in various display devices like TVs, monitors, and wearable devices, expanding its range of applications. Recently, innovative products like transparent displays and foldable displays have also emerged, making OLED’s future prospects even brighter.
Despite these numerous advantages, OLED has one notable flaw: the infamous burn-in phenomenon. The short lifespan of the organic compound-based light-emitting elements means that displaying the same color continuously for extended periods can leave a visible afterimage on the display itself. Since smartphones have a home screen, this often occurs when app icons from the home screen remain visible while web surfing or watching videos. Efforts to find new organic compounds and solve the burn-in issue continue.
In the fiercely competitive display market where technologies emerge and disappear, OLED appears poised to hold the top spot for the foreseeable future. Having evolved beyond conventional displays, OLED promises to lead us into the future. Just how far can OLED grow? Could a new display surpassing OLED ever emerge? The future of light, pioneered by OLED, is highly anticipated.
