AMOLED

AMOLED (active-matrix organic light-emitting diode; /ˈæmoʊˌlɛd/) 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.

Magnified image of the AMOLED screen on the Nexus One smartphone using the RGBG system of the PenTile matrix family

Since 2007, AMOLED technology has been used in mobile phones, media players, TVs and digital cameras,^[1] and it has continued to make progress toward low-power, low-cost, high resolution and large size (for example, 88-inch and 8K resolution) applications.^{[2][3][4][neutrality is disputed]}

Primary colors shown on the Dynamic AMOLED displays of the Galaxy Note 10 line

Design

Schematic of an active-matrix OLED display

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.^[5]

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.^[6]

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.^[7]

History

AMOLED was developed in 2006. Samsung SDI was one of the main investors in the technology, and many other display companies were also developing it. One of the earliest consumer electronics products with an AMOLED display was the BenQ-Siemens S88 mobile handset^[8] and, in 2007, the iriver Clix 2 portable media player.^[9] 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.^[10]

Future development

Samsung foldable smartphones

Manufacturers have developed in-cell touch panels, integrating the production of capacitive sensor arrays in the AMOLED module fabrication process. In-cell sensor AMOLED fabricators include AU Optronics and Samsung. Samsung has marketed its version of this technology as "Super AMOLED". 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.^[11]

Comparison to other display technologies

Compared to other display technologies, AMOLED screens have several advantages and disadvantages.

AMOLED displays can provide higher refresh rates than passive-matrix,^{[not specific enough to verify]} often have response times less than a millisecond, and they consume significantly less power.^[12] This advantage makes active-matrix OLEDs well-suited for portable electronics, 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 QVGA 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. ^[13] Because the black pixels turn completely off, AMOLED also has contrast ratios that are significantly higher than LCDs.^[14]

AMOLED displays may be difficult to view in direct sunlight compared with LCDs because of their reduced maximum brightness.^[15] Samsung's Super AMOLED technology addresses this issue by reducing the size of gaps between layers of the screen.^[16][17] 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.^[18][19]

Flagship smartphones sold in 2020 and 2021 used a Super AMOLED. Super AMOLED displays, such as the one on the Samsung Galaxy S21+ / S21 Ultra and Samsung 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.^[20][21][22] 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.^[23] On the other hand, compared with the IPS, the yield rate of AMOLED is low; the cost is also higher.

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. The display technology itself is not improved. According to Samsung, Super AMOLED reflects one-fifth as much sunlight as the first generation AMOLED.^[24][25] The generic term for this technology is One Glass Solution (OGS).

Comparison

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.

Term	Reso- lution	size (inches)	PPI	Color depth (bits)	Pixel layout	Used in
AMOLED	0320×240	2.2	182			iriver clix 2
		2.6	154		RGBG PenTile	Nokia N85
AMOLED Capacitive Touchscreen	0640×360	3.2	229			Nokia C6-01
Super AMOLED		3.5	210		RGB S-Stripe	Nokia N8
		4.0	184			Nokia 808 PureView
	0720×720	3.1	328			BlackBerry Q10
	0854×480	3.9	251		RGBG PenTile	Nokia N9
	0800×480	4.0	233			Samsung Galaxy S
	0960×540	4.3	256		RGB S-Stripe	Samsung Galaxy S4 Mini
	1280×768	4.5	332		RGBG PenTile	Nokia Lumia 1020
Super AMOLED Plus	0800×480	4.3 (4.27)	218		RGB stripe	Samsung Galaxy S II
Super AMOLED Advanced	0960×540	4.3	256		RGBG PenTile	Motorola Droid RAZR
HD Super AMOLED	1280×800	5.3 (5.29)	285			Samsung Galaxy Note
	1280×720	5.0	295		RGB S-Stripe	BlackBerry Z30 Samsung Galaxy J7 Samsung Galaxy J5 Samsung Galaxy E5 Samsung Galaxy J3 (2016)
		4.7 (4.65)	316		RGBG PenTile	Samsung Galaxy Nexus
		4.7 (4.65)	316		RGB S-Stripe	Moto X (1st generation)
		4.8	306		RGBG PenTile	Samsung Galaxy S III
		5.6 (5.55)	267		RGB S-Stripe	Samsung Galaxy Note II
		5.6 (5.55)	267			Samsung Galaxy Note 3 Neo
HD Super AMOLED Plus	1280×800	7.7	197		RGB stripe	Samsung Galaxy Tab 7.7
Full HD Super AMOLED	1920×1080	5.5	400		RGBG PenTile	Meizu MX5
		5.0 (4.99)	441			Samsung Galaxy S4
		5.0 (4.99)	441			OnePlus X
		5.0 (4.99)	441			Google Pixel
		5.2	423			Motorola Moto X (2nd gen)
		5.1	432			Samsung Galaxy S5
		5.5	401			OnePlus 3 OnePlus 3T OnePlus 5
		5.7	388			Samsung Galaxy Note 3
Full HD+ Super AMOLED	2160×1080	6.0	402			Google Pixel 3
		6.0	402			Huawei Mate 10 Pro
	2220x1080	6.01	411			Samsung Galaxy A8+ (2018)
Full HD+ Super AMOLED	2220x1080	5.61	441			Samsung Galaxy A8 (2018)
Super Retina HD	2436×1125	5.8 (5.85)	458			Apple iPhone X iPhone XS iPhone 11 Pro
	2688×1242	6.5 (6.46)				iPhone XS Max iPhone 11 Pro Max
WQHD Super AMOLED	2560×1440	5.1	577			Samsung Galaxy S6 Samsung Galaxy S6 Edge Samsung Galaxy S6 Active Samsung Galaxy S7 Samsung Galaxy S7 Active
		5.2	564			Microsoft Lumia 950
		5.2	565			Motorola Droid Turbo
		5.4	540			BlackBerry Priv
		5.5	534			BlackBerry DTEK60 Samsung Galaxy S7 Edge Google Pixel XL Alcatel Idol 4S vodafone smart platinum 7(Alcatel Sol Prime) Moto Z Moto Z Force ZTE Axon 7
		5.7	515	8		Samsung Galaxy Note 4 Samsung Galaxy Note 5 Samsung Galaxy S6 Edge+ Nexus 6P Samsung Galaxy Note 7
		5.7	518			Microsoft Lumia 950 XL
	2960×1440	5.8	571			Samsung Galaxy S8 Samsung Galaxy S9
		6.2	529			Samsung Galaxy S8+ Samsung Galaxy S9+
		6.3	521			Samsung Galaxy Note 8
		6.4	514			Samsung Galaxy Note 9
WQXGA Super AMOLED	2560×1600	8.4	359			Samsung Galaxy Tab S 8.4
		10.5	287		RGB S-Stripe	Samsung Galaxy Tab S 10.5
3K AMOLED	2880×1600	3.5	615		(unknown)	HTC Vive Focus Plus[26]
Dynamic AMOLED	2280x1080 3040x1440 2280x1080 3040x1440 3040x1440	5.8 6.1 6.3 6.4 6.8	438 550 401 522 498			Samsung Galaxy S10e Samsung Galaxy S10 Samsung Galaxy Note 10 Samsung Galaxy S10+ Samsung Galaxy Note 10+ Samsung Galaxy Fold Samsung Galaxy Z Flip
Fluid AMOLED	3120x1440	6.67	516			OnePlus 7 Pro
Dynamic AMOLED 2X	2208×1768 2400x1080 3200x1440	7.6 6.1 6.4 6.7 6.8 6.9	373 (Display resolution for Samsung Galaxy Z Fold 2) 386 (External display resolution for Samsung Galaxy Z Fold 2) 563 525 511 421 394 515 411 374 (Display resolution for Samsung Galaxy Z Fold 3) 389 (External display resolution for Samsung Galaxy Z Fold 3)		RGBG PenTile	Samsung Galaxy S20 Samsung Galaxy S20+ Samsung Galaxy S20 Ultra (Samsung Galaxy Note 20) (Samsung Galaxy Note 20 Ultra) Samsung Galaxy Z Fold 2 Samsung Galaxy S21 Samsung Galaxy S21+ Samsung Galaxy S21 Ultra Samsung Galaxy S21 FE Samsung Galaxy Z Fold 3 Samsung Galaxy Z Flip 3 Samsung Galaxy S22 Samsung Galaxy S22+ Samsung Galaxy S22 Ultra Samsung Galaxy Z Fold 4 Samsung Galaxy Z Flip 4 Samsung Galaxy S23 Samsung Galaxy S23+ Samsung Galaxy S23 Ultra Samsung Galaxy Z Fold 5 Samsung Galaxy Z Flip 5 Samsung Galaxy S24 Samsung Galaxy S24+ Samsung Galaxy S24 Ultra

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.^[27]

So far, Samsung plans on branding the newer displays as Youm,^[28] or y-octa.^[29]

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

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External links

• Craig Freudenrich. Types of OLEDs: Passive and Active Matrix at HowStuffWorks