In this blog post, we will look at how smartphones and display technology have evolved so far and predict how far they will evolve in the future.
What is the most brilliant invention of the 21st century? Smartphones, which are called the key to realizing ubiquitous computing and computers in the palm of your hand, are worthy of this honor. No matter where you go, you can easily find people looking at their smartphones. Smartphones have gone beyond simple communication devices to become a repository of information and the center of our lives.
Since Steve Jobs introduced the iPhone to the world, leading global companies have built a unique ecosystem in the smartphone market through astronomical investments. Equipped with high-performance cameras, CPUs, and large memory capacities, smartphones began to replace many portable electronic devices with their overwhelming specifications. The development of smartphones was not limited to hardware. The convergence of software greatly expanded the user experience, and with the emergence of various applications and services, smartphones became an ecosystem in themselves. This fundamentally changed people’s lifestyles and ushered in a new era of anytime, anywhere access to information and communication. With the spread of wireless Internet and improved awareness, people began to create their own content on smartphones, ushering in the era of one-person media. Many people began to view the text and images flooding their smartphones. The smartphone screen, which displays text and images, became increasingly important. In response to consumer demand, fierce competition arose in the market for superior displays. Thanks to competition in smartphone displays, brighter, clearer, more colorful, and more accurate displays continued to be developed. As improvements to existing displays became insufficient, people began to create new types of displays.
After repeated research, OLED (Organic Light Emitting Diode) became the new standard, showing many differences from other existing displays.
The only display technology available in the early days was CRT, or cathode ray tube. This is the bulky television screen that our parents used to watch long ago. It utilized the phenomenon of electrons fired from an electron gun hitting a panel to emit light, but 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 the point where it could be implanted in electronic devices at the end of the century, solving all the problems of CRTs.
LCD led to larger and slimmer screens, and CRTs disappeared into the annals of history. LCDs consist of a backlight panel that emits light and a liquid crystal that expresses colors. The light emitted by the backlight panel passes through a liquid crystal with a type of polarizing structure and then passes through the front polarizing plate to produce the final output.
The smallest display unit, called a pixel, consists of three elements: red, green, and blue. The contrast and color are determined by the degree of polarization of each element. Technically simple and easy to manufacture, LCDs advanced rapidly and dominated the display market for a while. Plasma display panels (PDPs) appeared with the promise of overtaking LCDs, but they were unable to compete with the efficiency and low power consumption of LCDs.
However, the backlight of LCDs had a fatal flaw despite its many advantages. LCDs, which block the light emitted from the backlight panel, had less light output than displays that emit light. Due to this structural feature, the screen was difficult to see under strong sunlight. Since colors are expressed by blocking white light, the color reproduction rate, which is the ability to accurately express the desired color, could not be raised above a certain level.
Due to the nature of smartphones, which are often used outdoors, there was a growing need for displays that were slightly brighter, more colorful, and clearer than natural LCD screens. In response to this demand, organic light-emitting diodes (OLEDs) were developed, which solved the structural problems of LCDs. OLEDs are displays that emit light directly using the self-illuminating effect of fluorescent organic compounds when an electric current is applied.
OLEDs use three types of organic materials that emit red, green, and blue wavelengths instead of backlights, enabling thin film formation. In addition, OLEDs can be used to create flexible displays that can be bent freely. Because OLEDs emit light directly, they have better color reproduction and contrast ratios than LCDs and consume very little power.
Thanks to these features, OLED is being adopted not only in smartphones but also in various display devices such as TVs, monitors, and wearable devices, expanding its range of applications. In particular, innovative products such as transparent displays and foldable displays have recently appeared, making the future of OLED even brighter.
Despite its many advantages, OLED has one drawback, which is the well-known burn-in phenomenon. The light-emitting elements that use organic compounds have a short lifespan, so when the same color is displayed continuously for a long time, a visible image remains on the display itself. Smartphones have home screens, so this often occurs when surfing the web or watching videos, as the app icons on the home screen remain visible. Efforts to find new organic compounds to solve the burn-in phenomenon are ongoing.
In the fierce display market, where various technologies emerge and disappear, OLED is likely to remain the best display for the foreseeable future. How far can OLED, which has evolved from conventional displays and will lead us into the future, grow? Will a new display that is superior to OLED appear? We look forward to the future of light led by OLED.
