OLED display backplanes, part 1 of 7: introduction & PMOLED

The display backplane is the grid of thin-film transistors (TFTs) sitting behind the pixels, switching and feeding each one. It is one of the major constraint on what an OLED display can do, and is also the component that actually consumes (or wastes, really) most of the energy, more than the OLED emitters themselves.

This article is the first in a new seven-part series that will offer a practical guide to the backplane technologies of today, and of the future. Across the parts we explain how each one works, how it is manufactured, which products use it, and where its roadmap is heading. The journey runs from the simplest displays of all to the most advanced backplane in development today:

• Part 1: Introduction to the series, and PMOLED (the backplane-free OLED).
• Part 2: a-Si: the backplane that built the LCD industry but could never power OLEDs.
• Part 3: LTPS: the laser-crystallized silicon that finally drove OLED.
• Part 4: Oxide TFT (IGZO): the scalable, low-power newcomer.
• Part 5: LTPO: the flagship hybrid TFT that enables VRR
• Part 6: HMO: high-mobility oxide, the future industry backplane?
• Part 7: Organic TFTs and silicon CMOS microdisplay backplanes

What a backplane actually is

The backplane of the display is defined as the materials or components that are placed between the substrate of the display and the frontplane, which is the part that is responsible to emit the light. The task of the backplane is to control the frontplane (the “pixels”).