OLED - The Panel That Folds Over LCD Panels.

You've probably heard the term OLED which stands for Organic Light Emitting Diodes is one of the most significant revolution in the sector of display panels.

Most of the phones in the market like the IPhone 11 , not the 11 pro , use LCD display which stands for Liquid Crystal Display. The liquid crystals fall somewhere in between a solid and liquid , help them to change their molecular orientation when an electrical current is applied. This is incredibly useful as it helps us to use the molecules to change the direction of light that is passing through the liquid crystal. These liquid crystals don't produce their own light and require a backlight. But in modern LCD displays LED backlighting is used with a backlight uniformity filter, added to ensure even lighting across the panel.Next the light passes through the polarization film which only let's light travelling in a horizontal orientation to pass through, followed by liquid crystal group and another polarizing filter oriented 90 degrees to the first. If you are familiar to polarizing filters, you know that light does not pass through two filters when they are aligned perpendicular to each other. So, light depends on this liquid crystal layer to orientate the light to allow it to pass through the second filter. The liquid crystal layer is sandwiched between two electrodes and two pieces of etched glass, forcing the liquid crystal molecules into a near predictable 90 degree twist. When a voltage is applied through the electrodes, the crystal molecules begin to realign in the direction of the current, a larger voltage will result in a full 90 degree twist. As light passes through, it will follow the direction of the crystal molecules before encountering the second polarization filter. So, the second polarization filter acts as a controllable light valve. If light is allowed to pass, it will pass through a colored filter, giving it one of three colors. Red , Blue or Green. This structure is called a sub-pixel. The combination of three sub-pixels with red, green and blue filters giving you a single traditional RGB Liquid Crystal. This brings significant characteristics of LCD displays. The first is that, even when the panel is displaying a black image, the backlight is always on, causing a large battery drain and some light leakage at pixel boundaries and the edges of the screen, which negatively affects the screen contrast ratio.

OLED work very differently than LCD in a few key ways. Foe starters, there is no backlight. Instead, each pixel is self illuminating through the light emitting process called electrophosphorescence. There are two organic compounds, called the emissive and conductive layers that are sandwiched in between an anode and a cathode. As an electrical current flows from the cathode to the anode, electrons are given to the emissive layer, and removed from the conductive layer. The electrons in the emissive layer now migrate to fill the holes in the conductive layer. When they do, extra energy is released as a photon. This whole process and structure is controlled by the TFT Matrix and the entire structure is placed on a substrate of either glass or polymer. As there is no backlight and each individual pixel is individually controlled, substantial power saving can occur when dark or black images are displayed. In addition OLED panels are significantly thinner and lighter than their LCD counterparts, allowing for slimmer displays and razor sharp bezels and flexible screens, also foldable screens. OLED panels have high brightness and true zero pixel value, leading to insane contrast ratios of over 1,000,000:1. Blacks are inky and colors are more vibrant and localized brightness can greatly improved. The chief limiting factor is burn in. This happens because of static displays like the UI elements. These static elements now appear as ghost images. This happens due to the breakdown of organic compounds in the pixel, when displaying the same picture. But this technology comes with a price as OLED's are almost twice the price of LCD panels. But companies are offering OLED screens for very low prices, and companies like LG working on transparent OLED technology.

OLED seeks to change the way we use, interact and view information on, and will keep improving the quality.

Picture Source : Real Engineering.