AMOLED

Each pixel is driven by its own Thin-Film Transistor (TFT). The transistor stays with that pixel, so the panel can refresh faster, hold a brighter image, and address pixels individually.

The emitting element is an Organic Light Emitting Diode (OLED). Current through the diode makes that pixel emit, and the transistor selects which pixel receives it. Phones, watches, and tablets use AMOLED when the screen needs that per-pixel control.

How Each Pixel Is Driven

The backplane places one transistor at every pixel, rather than sharing a single switch across a row.

• Own transistor. Each pixel is driven by its own thin-film transistor, so the panel doesn’t borrow one driver for the whole row.
• Individual address. The circuit can change one pixel and leave the others alone.
• Faster refresh. With the transistor already at the pixel, the panel can refresh faster than a grid that must step through every intersection.
• Held brightness. The pixel’s transistor can hold a brighter image, because the pixel stays driven instead of waiting for the next pass of a shared row.

Where These Panels Are Used

A thin color screen that must stay bright while only part of the picture changes is the usual fit. Phones, watches, tablets, and some laptops are the common cases.

A small readout that can accept a slower response often keeps the simpler grid, because that panel is cheaper to build.

Active-Matrix and Passive-Matrix Compared

A Passive-Matrix Organic Light-Emitting Diode (PMOLED) panel uses a row-and-column grid. It is simpler and cheaper, and it has a slower response.

Trait	Active-Matrix Panel	Passive-Matrix Panel
Drive	Each pixel is driven by its own thin-film transistor	A row-and-column grid shares the drive
Addressing	Pixels are addressed individually	Intersections on the grid share the drive
Refresh	The panel can refresh faster	Slower response
Brightness	The panel can hold a brighter image	Harder to hold a bright image on the shared grid
Build	More switching circuitry at each pixel	Simpler and cheaper