AMOLED

AMOLED (active-matrix organic light-emitting diode; ) is a type of OLED display device technology. OLED describes a specific type of thin-film-display technology in which organic compounds form the electroluminescent material, and active matrix refers to the technology behind the addressing of pixels.

Since 2007, AMOLED technology has been used among mobile phones, media players, TVs and digital cameras, and the current progress over this technology is in lower power usage, lower cost, better resolution and specifically for larger screen (e.g. 8k screens).

Design

An AMOLED display consists of an active matrix of OLED pixels generating light (luminescence) upon electrical activation that have been deposited or integrated onto a thin-film transistor (TFT) array, which functions as a series of switches to control the current flowing to each individual pixel.

Typically, this continuous current flow is controlled by at least two TFTs at each pixel (to trigger the luminescence), with one TFT to start and stop the charging of a storage capacitor and the second to provide a voltage source at the level needed to create a constant current to the pixel, thereby eliminating the need for the very high currents required for passive-matrix OLED operation.

TFT backplane technology is crucial in the fabrication of AMOLED displays. In AMOLEDs, the two primary TFT backplane technologies, polycrystalline silicon (poly-Si) and amorphous silicon (a-Si), are currently used offering the potential for directly fabricating the active-matrix backplanes at low temperatures (below 150 °C) onto flexible plastic substrates for producing flexible AMOLED displays.

History

AMOLED display research was initiated by Steven Van Slyke and Ching Wan Tang, who pioneered the organic light-emitting diode (OLED) technology at Eastman Kodak Co. in 1979. The first AMOLED displays were introduced in the early 2000s, with Samsung being the first company to commercialize AMOLED displays. One of the earliest consumer electronics products with an AMOLED display was the mobile handset, BenQ-Siemens S88. In 2007, the iriver Clix 2 portable media player. In 2008 it appeared on the Nokia N85 followed by the Samsung i7110 - both Nokia and Samsung Electronics were early adopters of this technology on their smartphones.

Future development

Manufacturers have developed in-cell touch panels, integrating the production of capacitive sensor arrays in the AMOLED module fabrication process. Researchers at DuPont used computational fluid dynamics (CFD) software to optimize coating processes for a new solution-coated AMOLED display technology that is competitive in cost and performance with existing chemical vapor deposition (CVD) technology. Using custom modeling and analytic approaches, Samsung has developed short and long-range film-thickness control and uniformity that is commercially viable at large glass sizes.

Comparison to other display technologies

AMOLED displays are proved to be better at providing higher refresh rates than those of passive-matrix,often have response times less than a millisecond, and they consume significantly less power. This advantage makes active-matrix OLEDs well-suited for portable electronics due to its high productivity for everyday use. AMOLED also stands higher in the field of less power consumer than OLED, because "each pixel have their own light and can be controlled leading to better power control and amplification", where power consumption is critical to battery life.The amount of power the display consumes varies significantly depending on the color and brightness shown. As an example, one old OLED display consumes 0.3 watts while showing white text on a black background, but more than 0.7 watts showing black text on a white background, while an LCD may consume only a constant 0.35 watts regardless of what is being shown on screen. A new FHD+ or WQHD+ display will consume much more. Because the black pixels turn completely off, AMOLED also has contrast ratios that are significantly higher than LCDs.

AMOLED displays are often difficult to see in direct sunlight compared with LCDs because of their reduced maximum brightness.Super AMOLED, a modern technology, addresses this issue by reducing the size of gaps between layers of the screen. Additionally, PenTile technology is often used for a higher resolution display while requiring fewer subpixels than needed otherwise, sometimes resulting in a display less sharp and more grainy than a non-PenTile display with the same resolution.
The organic materials used in AMOLED displays are very prone to degradation over a relatively short period of time, resulting in color shifts as one color fades faster than another, image persistence, or burn-in.

Marketing terms

Super AMOLED

''Super AMOLED'' is a marketing term created by Samsung for an AMOLED display with an integrated touch screen digitizer, the layer that detects touch is integrated into the display, rather than overlaid on top of it and cannot be separated from the display itself. When compared with a regular LCD display an AMOLED display consumes less power, provides more vivid picture quality, and renders faster motion response as compared to other display technologies such as LCD. However, Such type of AMOLED is even better at this with 20% brighter screen, 20% lower power consumption and 80% less sunlight reflection. According to the Samsung, Super AMOLED reflects one-fifth as much sunlight as the first generation AMOLED. The generic term for this technology is One Glass Solution (OGS), a touchscreen technology that combines the touch sensor and cover glass into a single layer, reducing overall thickness and improving optical clarity. This is achieved by coating and etching the ITO (Indium Tin Oxide) layer directly onto the cover glass, eliminating the need for a separate sensor glass and an air gap.

Super AMOLED displays, while known for their vivid colors and deep blacks, also have some drawbacks, including higher manufacturing costs, potential for screen burn-in, and shorter lifespan compared to some other technologies.

Devices with AMOLED and SuperAMOLED

Below is a mapping table of marketing terms versus resolutions and sub-pixel types. Note how the pixel density relates to choices of sub-pixel type.

Display devices with AMOLED technologies

Flagship smartphones sold in 2020 and 2021 used AMOLED. These displays, such as the one on the Galaxy S21+ / S21 Ultra and Galaxy Note 20 Ultra have often been compared to IPS LCDs, found in phones such as the Xiaomi Mi 10T, Huawei Nova 5T, and Samsung Galaxy A20e. For example, according to ABI Research, the AMOLED display found in the Motorola Moto X draws just 92 mA during bright conditions and 68 mA while dim.Google/Motorola Mobility Display a Bright Efficient Future
ABI Research On the other hand, compared with the IPS, the yield rate of AMOLED is low; the cost is also higher.

Future

Future displays exhibited from 2011 to 2013 by Samsung have shown flexible, 3D, transparent Super AMOLED Plus displays using very high resolutions and in varying sizes for phones. These unreleased prototypes use a polymer as a substrate removing the need for glass cover, a metal backing, and touch matrix, combining them into one integrated layer.

So far, Samsung plans on branding the newer displays as Youm, or y-octa.

Also planned for the future are 3D stereoscopic displays that use eye-tracking (via stereoscopic front-facing cameras) to provide full resolution 3D visuals.

See also

* List of flat panel display manufacturers
*microLED
*OLED

References

External links

*

{{Display technology

Mobile phones
Conductive polymers
Display technology
Molecular electronics
Optical diodes
Organic electronics