When looking at smartphone specifications (which are all explained here), you may have come across terms such as OLED and AMOLED in reference to the display. But what do they mean? What’s the difference? And which one is better?
OLED refers to a type of display technology that rivals LCDs in which organic molecules produce light when an electric current is passed through them. AMOLED is an ‘Active Matrix’ subtype of OLED, not a rival. ‘Active Matrix’ refers to how the individual pixels on the display are powered up.
To better understand these display technologies, let’s look at them in more detail.
OLED
In smartphone display technology, there are two main types of displays– LCDs and OLED displays. LCDs use liquid crystals in the display (hence the name Liquid Crystal Display) and require a backlight to display anything on the screen.
OLED stands for Organic Light-Emitting Diode. This technology uses LEDs with organic molecules that light up when a current is passed through them. Unlike liquid crystal displays (LCDs) that require a backlight panel to display anything on the screen, OLED pixels are controlled individually and produce their own light.
Because of this, OLED displays have great image quality and high contrast. Since there is no backlight, the pixels can be turned off completely to produce “true” blacks. And doing away with the backlight panel also makes OLEDs much thinner and more flexible than LCDs.
OLEDs are similar to LEDs in that they both essentially use a light-emitting diode (LED) that lights up when electricity is passed through it to illuminate the display. The major difference is that OLEDs contain organic, carbon-based molecules, and it also uses less energy.
You’re very unlikely to find a smartphone with an LED display. Those are mostly found in TVs. Most smartphones that don’t have an LCD screen have an OLED display or a subtype of it such as AMOLED or P-OLED.
How do OLEDs work?
OLED display panels are made of various components, the main one being the carbon-based organic material that emits light when electricity is applied to it. The basic structure of an OLED comprises an emissive layer and a conductive layer placed between a cathode and an anode, through which electricity flows.
The rest of an OLED panel contains a substrate on which the entire aforementioned OLED layer “sandwich” (or front plane) rests. There is also a backplane with the electronics that drive the entire system.
When power is supplied from the battery to the OLED display, an electrical current flows from the cathode, through the organic layers (emissive layer and conductive layer), to the anode, and that results in light being emitted. The colour of the light depends on the type of organic molecule in the emissive layer.
The brightness and intensity of the light are dependent on the amount of electrical current being passed through. The more current you have, the brighter the display.
OLED displays use two types of matrices (or matrixes?) to supply a current to the organic layers– a passive matrix and an active matrix, known as PMOLED and AMOLED, respectively. You are most likely to find an AMOLED display on a smartphone than a PMOLED display.
Pros and cons of OLED displays
| Advantages | Disadvantages |
| No backlight | Shorter life span than LCD |
| Energy efficient | Visible changes over time |
| Good contrast and image quality | Damages easily in water |
| High screen brightness | Expensive and complex to make |
| Thin and flexible | |
| Fast response time | |
|
Large viewing angle |
Other types of OLED displays
There are several types of OLED displays such as Transparent OLED, White OLED, and Top-emitting OLED. These are found in other applications other than smartphone displays such as heads-up displays (HUD), or as replacements for fluorescent lights in the case of White OLED.
However, a new type of OLED has made its way into smartphone displays in recent years, and that’s P-OLED (not to be confused with PMOLED). P-OLED stands for Polymeric Organic Light-Emitting Diode. It is exactly the same as an ordinary OLED display save for the fact that it has a plastic substrate instead of a glass one.
Because plastic is more flexible than glass, P-OLED displays are gaining more and more popularity for their versatility. Some manufactures may state in their phone specs that their devices have a Foldable OLED display. This is basically the same as a P-OLED display in that, as the name suggests, it is also flexible.
AMOLED
As already mentioned a couple of times, an AMOLED display is not a competitor of OLED, but rather a subcategory or different form of OLED technology. AMOLED stands for Active Matrix Organic Light-Emitting Diode. ’Active Matrix’, similar to ‘Passive Matrix’, refers to the way the display is powered up.
Passive Matrix OLEDs (PMOLEDs) are made up of strips of the cathode, organic layers, and then strips of the anode. The cathode and anode strips are positioned perpendicular to each other and emit light where they intersect when an external circuitry applies current to them.
Source: howstuffworks.com
On the other hand, an Active Matrix OLED display does not require external circuitry to provide a current, nor does it use strips of anode and strips of the cathode. Instead, AMOLED displays have a full layer of the cathode and a full layer of anode above and below the organic layer.
The anode of an AMOLED display sits above a thin film transistor (TFT) array that forms a matrix. The acronym AMOLED gets its “Active Matrix” name from the fact that the TFT matrix itself is the circuit that determines which pixels get turned on and off to create an image, not an external circuit as is the case with PMOLED displays.
Types of proprietary AMOLED
Some manufacturers have taken the AMOLED technology and modified it to suit their needs. The results are usually improved display specs, but the technology remains AMOLED at its core. Therefore, when a phone manufacturer makes a change to the AMOLED technology, they often attach their own prefix to the AMOLED acronym, perhaps mainly for marketing purposes.
Samsung is popular for doing this but they are not the only ones. Below are some examples of versions of AMOLED that some manufacturers have come up with.
Super AMOLED
Super AMOLED displays are a product of Samsung and were introduced in smartphones back in 2010. They are basically an AMOLED display with touchscreen technology integrated into it. And because a Super AMOLED display doesn’t have a separate touch-sensitive layer, it is the thinnest type of smartphone display on the market.
Super AMOLED displays are better than normal AMOLED displays when it comes to image quality and visibility in direct sunlight. According to Samsung, the brightness of a Super AMOLED screen is 20% brighter than an ordinary AMOLED but uses 20% less power.
Dynamic AMOLED
Dynamic AMOLED is basically the same as Super AMOLED, except that Dynamic AMOLED is HDR10+ certified. Samsung claims that that means that the display can produce cinema-grade colour and contrast. It also claims it reduces the blue light that comes from the display to help reduce strain on the eyes.
Recent developments have seen the introduction of Dynamic AMOLED x2. This is an improvement on Dynamic AMOLED, with notable improvements in colour, HDR, and brightness. It supposedly has the best colour accuracy that lets you see visuals just as they should be.
Fluid AMOLED
Similar to Samsung, oftentimes, other smartphone manufacturers use unique terms to market their version of an already existing technology with a slight difference. Fluid AMOLED is one of them, courtesy of OnePlus. Basically, their Fluid AMOLED displays are just AMOLED displays with a higher screen refresh rate of 90Hz.
Having a high screen refresh rate has the advantage of creating smooth animations because the display will be refreshing quicker than usual. But OnePlus is not the only OEM (original equipment manufacturer) that features AMOLED displays with fast screen refresh rates. However, not everyone calls it Fluid AMOLED.
Conclusion
So, what have we learned? OLED and AMOLED are not two competing display technologies nor is one an improved version of the other. AMOLED is simply a type of OLED that has a TFT array that powers individual pixels on and off.
A good comparison of smartphone display technologies should be made between OLED displays and LCDs. The two technologies are fundamentally different and each has its advantages and disadvantages.