An Organic Light Emitting Diode or OLED is an organic electroluminescent diode that converts electric current to light. Relatively new to the market, technologies are progressing in OLED exponentially as companies strive to make full use of this unique and versatile technology. Due to the OLED cathode's highly reflective nature, there have been concerns about OLED television displays' potential glare.
OLED TVs do not have a glare due to circular polarizers and anti-reflective coatings that counteract the OLED display's reflective tendencies. These specialized coatings reduce diffuse reflectance to below 0.1%, making your OLED TV less reflective than most LCD-based television displays.
To understand the enhanced capacities of modern OLED technology, including reflective tendencies, you first need to understand what the OLED is and how it works, and what makes it different from the LED technology you are familiar with in your homes.
What Is an OLED?
OLEDs are solid-state devices made up of several thin layers of organic material that collectively make up a width of only 1/50th of a human hair. Unlike LEDs other point light sources with a backlight, OLEDs are self-illuminating due to its organic makeup and are thus thinner than the LCDs found on the market.
An OLED structure is a layer of emissive material held between a cathode, which injects electrons and an anode that removes them. The emissive layer of an OLED is composed of various electron-transporting materials combined with a dopant emitter, while the substrate may vary between glass, plastic, or foil.
The anode structure is usually transparent and is typically made from indium tin oxide, and functions to inject holes into the various layers. Alternatively, the cathode has lesser work functions and is made of barium or calcium that enables electron injection into the multiple layers of the OLED. As a result of the excited state, the substructure's radiation is perceived as light.
Contrast and deep color saturation are created by individually addressing the red, green, and blue OLEDs inside each pixel. OLEDs thus deliver differentiated and high-performance displays with lower energy consumption than typical LED displays in half of the space.
The condensed phases involved in the OLED process are closely related to the chemiluminescence and bioluminescence that occur in nature. This process mirrors the enchanting glow of fireflies at night. In fact, the firefly's luminous intensity is behind many studies in advance of OLED technology.
The manner in which the OLED emits an ultra-flat, glare-free light source has made the dream of paper-thin and flexible displays an attainable reality with implications in several new lighting applications.
How OLED Works
|Seal||Glass top plate|
|Cathode||Negatively charged electrode that attracts electrons|
|Emissive Layer||A layer of organic molecules or polymers transport electrons to the cathode|
|Conductive Layer||A layer of organic molecules or polymers that transport holes from the anode|
|Anode||Positively charged electrode which attracts electrons or anions|
|Substrate||Glass bottom plate|
The process of OLED illumination is technical; however, the basic working of an OLED are as follows:
- Electrical current is applied to the anode and cathode layer, and energy travels from the cathode through the organic emissive and conductive layers to the anode layer.
- The current supplies electrons to the emissive layer and transports electrons from the conductive layer.
- The removal of electrons from the conductive layer leaves holes, which need to be filled with electrons.
- The holes jump from the conductive layer to the emissive layer filled with electrons to recombine with the electrons.
- As the electrons fill the holes, extra energy is released in the form of bright electroluminescent light.
- Our naked eyes perceive the light as it becomes visible through the glass top plate.
OLED vs. LED
An LCD TV uses a thin layer of liquid crystal solution between transparent glass panels. A matching grid of transistors supplies an electric charge that controls the crystals to open and close. While the liquid crystals form the image, they do not create light and thus need a backlight source to illuminate them.
Light-emitting diodes or LEDs entered the market as a replacement for the earlier cold cathode fluorescent lamps that backlit the LCD. The LED is made for greater optical range, color saturation, and power efficiency. Most LEDs on the market are LCDs with an LED lighting system and can be called LED TVs, SUHD TVs, Super UHD TVs, or even QLEDs (Quantum Dot LEDs).
On the other hand, OLEDs are self-illuminating due to their organic materials. They require no backlight, making them thinner, more malleable, and operating less power than their LED counterparts.
Do OLEDs Have More Glare Than LEDs?
OLEDs' emissive-based technology functions to convert electricity into light, whereas LEDs are reflective to some degree. The metallic cathode in the OLEDs functions somewhat like a mirror with an almost 80% level of reflection, leading to glare challenges in bright ambient conditions such as outdoor lighting.
However, engineers have taken this high reflective tendency in OLED displays and utilize circular polarizers and anti-reflective coatings to counteract the glare effects. In fact, the specialized coatings have reduced the diffuse reflectance to below 0.1%.
This percentage equates to a photopic contrast level of 5:1 in simulated outdoor environments of 10,000 FC. In fact, through intensive testing in controlled light conditions, the OLED is only outperformed by its QLED counterparts in reflection testing and achieved the results:
|Model||Total Reflection Percentage||Indirect Reflections Percentage||Calculated Direct Reflections Percentage|
|LG CX OLED||1.5%||0.2%||1.1%|
|LG B9 OLED||1.5%||0.2%||1.3%|
In terms of mobile phone OLED screens, the Galaxy S5 had a better score than its LCD competitors in reflectance, power usage, and brightness.
Advantages of OLEDs
There are many advantages to the OLED system, not limited to the variety of future applications such as displays, vehicle dashboards, home lighting and interior decor, and other forms of flexible displays. These advantages include:
- Perfect black: Deep and dark blacks are fundamental in achieving superior picture quality. Deeper blacks allow for greater contrast and more vivid color, resulting in more realistic and vibrant image quality. Since the black OLED display emits no light, the OLED systems deliver a pure black that LEDs cannot match their reliance on a backlight.
- Greater response rates: OLEDs deliver a greater response time, refresh rate, and input lag than other systems. Because the color and light source are located in one diode in the OLED system, they can change states at an accelerated rate of up to 1,000 times faster than LED TVs. This high response rate results in less motion lag and finer detail in fast motion content such as sports shows.
- Greater visuals from every angle: The self-emissive nature of the OLED system has a much broader angular distribution than LEDs. For example, at a 30° viewing angle, an OLED brightness decreases by only 30%, whereas an LED display suffers a 50% decrease in brightness. OLED pixels remain correct and unshifted even up to a 90° angle of viewing.
- Flexible and lightweight: Because of OLED technology's thinness and flexibility, they can be fabricated on flexible substrates that can be rolled up or embedded in clothes or fabrics. The flexibility in substrate materials also eliminates both the weight and fragility of glass embedded displays.
- Consume less power: OLEDs do not require backlighting such as LCD and LEDs by generating their light emission through electroluminescence. Thus, OLEDs have a lower power consumption than the traditional LED systems, which consume energy for backlighting. On average, OLEDs consume about 40% of the power of a typical LCD. This is particularly relevant to battery-operated handheld devices such as cell phones.
The lower energy consumption and potential applications make OLEDs a substantial part of our future lives. As new glare-proof coverings emerge, OLED displays' full clarity and brightness emerge to dominate the visual display arena.
Although OLEDs still have a shorter lifespan than LEDs and are susceptible to UV damage and moisture, as an emerging technology, OLED's are advancing by leaps and bounds. While the world's greatest minds are competing to harness the full potential of OLEDs, the technology has the potential to become mass-produced at a fraction of the cost of the initial offerings to date.