Explained: Why brands may prefer AMOLED displays over LCDs

The technology used for producing displays for mobile devices is broadly divided into two popular types — AMOLED and LCD. Some mobile devices even use OLED panels which are very similar to AMOLED technology. The underlying technologies that both AMOLED and LCD panels rely on are very different from each other. So, the leading smartphone manufacturers promote the various benefits depending on the type of display they’ve opted for their devices. However, more manufacturers are adopting AMOLED displays for higher-end devices while reserving the LCDs for less expensive handsets. Here, we will discuss the differences between these two display technologies.
What are AMOLED displays?
Before starting about AMOLED displays, we should first know the technology behind OLED displays. The key components in these displays are a Light Emitting Diode (LED). These little lights are compressed exponentially into even smaller sizes and are arranged in red, green, and blue clusters to create an individual pixel. These pixels can reproduce white light and multiple other colours that also include — red, green and blue.
The performance of these displays is slightly altered by the arrangement of the sub-pixels. For example, pentile vs striped pixel layouts help in improving the image sharpness, but the life spans of these pixels deteriorate for the smaller sizes. OLED or Organic Light Emitting Diode displays use a series of thin organic material films that are placed between two conductors in each LED. When current passes through them, these films are then used to produce light.
Meanwhile, AMOLED or Active Matrix Organic Light Emitting Diode tells us how each little OLED is controlled. This technology is different from the passive matrix technology which is a slower, less accurate and more complex grid system that is used to control individual pixels. In this technology, integrated circuits are present to control a charge sent down each column or row. On the contrary, AMOLED systems attach a thin film transistor (TFT) and capacitor to each LED. To access the correct pixels, these capacitors retain their charge in between refresh cycles when a row and column are activated.
Another display technology related to OLED is the one marketed by Samsung as Super AMOLED. Instead of it being a separate layer on top of the display, this display technology integrates the capacitive touchscreen right into the screens, which eventually makes them thinner.
What are LCDs?
LCDs or Liquid Crystal Displays reproduce colours very different from AMOLED displays. LCDs depend on the backlight as their sole light source and are not equipped with individual light-emitting components. Multiple backlights can be placed across a display for local dimming and to save power, but this is needed only for larger displays like TVs.
We know that white light is a mixture of all other visible colours in the spectrum and it doesn’t have an individual wavelength. So, LCD backlights create a pseudo white light which is then filtered into different colours in the liquid crystal element. Most LCDs produce pseudo white light with the help of a blue LED backlight filtered through a yellow phosphor coating.
Light is then passed through a crystal element after it is polarised. The crystal can be twisted to multiple degrees depending on the voltage applied to it. This adjusts the angle of the polarised light. The light is then passed through another polarised filter which is placed at 90 degrees from the first one weakening the light based on its angle. Eventually, a red, green, or blue colour filter is applied to this light and these sub-pixels are clustered into pixels to adjust colours across the display.
Rather than producing coloured light in each pixel, a combination of all these allows an LCD panel to control the amount of RGB light reaching the surface by selecting a backlight. LCD panels can either be active or passive matrix devices like AMOLED, but most modern smartphones are active.
Advantages of OLED display technology
The major benefit of the OLED display technology is the amount of control that can be applied over each pixel. These displays can produce deep blacks and a high contrast ratio by completely switching off the pixels. The ability to dim and turn off individual pixels even saves a bit of power and is great for viewing HDR content. The maximum amount of light reaches the display surface as there are fewer other layers on top of the LEDs which eventually results in brighter images with better viewing angles.
Why OLED displays are important for foldable devices
The key driving force behind the growth of curved edge displays and the latest foldable devices is the advancement of OLED display technology. These displays can be very thin as they use LEDs and minimal substrates. Moreover, the absence of a rigid backlight and innovations in flexible plastic substrates has enabled the development of flexible OLED-based displays.
The backlight requirement hinders complex LCDs to be built in such ways. Initially, flexible displays looked very promising for wearables, but now flagship mobile devices use these flexible OLED displays. However, there is a major concern about the number of times these displays can flex and bend before breaking. Samsung Galaxy Z Fold 3, Motorola Razr 5G and Huawei Mate XS are some of the foldable smartphones that are based on OLED display technology.