This article covers the principles and structure of organic light-emitting diodes (OLEDs), their key advantages and differences from LCDs, and explores the potential for OLEDs to become the next generation of displays. It also discusses the technical limitations faced by OLEDs and their various applications, and outlines their role and prospects in the future display market.
OLED, the display of the future
What is the most important sense you use to take in information? Most people would answer either sight or hearing. Of these, sight is an essential sense for communicating information and has been fundamental to the development of displays, which are visual display devices. Whether it’s a smartphone, a smart TV, a computer, or a big screen in a cinema, displays are closely associated with our lives and are the interfaces that make information visually meaningful. In a society where possessing various information capabilities has become a competitive advantage due to the development of networks, communications, and other technologies, displays, a medium that connects information to people and people to information, have also developed complementarily. Display engineering is a convergence of electrical engineering and materials engineering, and active research is being conducted on how to increase the resolution to realistically reproduce visual information, how to enable low-power operation, how to reduce the weight of displays to increase the cost-effectiveness of devices, and how to move toward larger and ultra-thin displays.
Displays have evolved from cathode ray tubes (CRTs) to liquid crystal displays (LCDs), with LCDs currently accounting for the majority of the display market. However, with the advent of organic light emitting diodes (OLEDs), OLEDs have become the next generation of displays with many advantages that LCDs lack. In this article, we will explain the principle and basic structure of OLEDs, their advantages and applications, and explore their potential as the next generation of displays.
The principle and basic structure of OLEDs
OLEDs are organic light-emitting diodes, which are characterised by their ability to emit light when an electric current is passed through them. In LCDs, the liquid crystals themselves don’t light up, so they rely on a backlight to display the screen, but OLEDs light up when an electric current flows through the organic material, providing a clearer picture. The basic principle of OLED is as follows A transparent electrode is used as an anode and a metal plate electrode is used as a cathode on the other electrode, and the OLED material is placed between the two electrodes. When a voltage is applied, electrons move from the cathode and holes move from the anode, causing the two carriers to recombine and emit light. The light emitted has a specific energy and can produce different colours of light.
The cross-sectional structure of an OLED cell consists of a cathode, an electron injection layer, an electron transport layer, an emissive layer, a hole transport layer, a hole injection layer, a hole injection layer, an anode, and a glass or plastic substrate. This simple structure allows OLEDs to create displays that are much thinner and lighter than LCDs.
Advantages of OLED
What makes OLEDs different from LCDs is that they are self-emitting. This leads to a few key advantages. First, they are high-definition and have excellent colour reproduction. Because OLEDs are self-luminous, they don’t need a backlight like LCDs, which means less light loss and a sharper picture quality. They can also display a wide range of colours, resulting in excellent colour reproduction, and the screen has high brightness and contrast.
Second, they have wider viewing angles. While LCDs are prone to colour distortion and darkening when viewed from the side, OLEDs have the same colour and picture quality from any angle. This is an important advantage, especially for large or portable devices like TVs and smartphones.
Third, they’re more energy efficient. OLEDs consume less power because they only light up the pixels they need. LCDs, on the other hand, require the backlight to be on all the time, which consumes a lot of unnecessary power. In this respect, OLEDs also help to extend battery life in portable devices such as smartphones and smartwatches.
Expanding applications
OLED technology is expanding into a variety of applications based on its ultra-thin and ultra-lightweight advantages. In particular, flexible displays using plastic substrates are playing an important role in enabling displays that can be bent. As a result, OLEDs are being used in various fields beyond conventional flat displays, such as smartphones, tablets, and even e-paper and wearable devices. Wearable devices, in particular, are devices that can be worn on the user’s body, and OLED’s flexibility and lightweight properties make them even more promising.
Flexible OLEDs also have great potential for applications in automobiles, aircraft, and consumer electronics. Innovations include curved displays to provide a more intuitive interface on the dashboard of a vehicle, or the use of OLEDs in consumer electronics to enhance the user experience.
Challenges of OLED
Despite OLED’s many advantages, there are still some technical challenges to overcome. For example, OLEDs still have a shorter lifespan than LCDs. In particular, blue OLEDs have a shorter lifespan, which affects the durability of the display as a whole. There are also cost limitations when it comes to larger sizes and higher resolutions. With current technology, it is expensive to produce large OLED panels, which limits commercial large-scale production.
OLEDs are also highly sensitive to environmental factors. Exposure to moisture and oxygen causes rapid degradation, and technologies are needed to prevent this. These technical challenges need to be addressed in future research.
Conclusion
OLEDs hold a lot of promise as the next generation of displays. The high definition, energy efficiency, and scalability to ultra-thin and flexible displays due to self-luminescence suggest that OLEDs will continue to play an important role in the display market. However, there are still challenges to be overcome, and technological advancements will need to continue. Korea is currently leading the global display market with LCD and AMOLED technologies, and will need to continue to develop more innovative OLED technologies to maintain global competitiveness and lead a new paradigm.
