I don't understand these statements:

"...smart displays and vibrant art pieces (that won’t fade over time)... However, when the display is turned off, the images become visible, which allows for information display without using any energy."

Nowhere does it say that the coloration can be changed, once applied. The different-sized particles are embedded in acrylic. So how does this enable a "smart display?" I guess you can say that a turned-off monitor can now show "information," but that information printed on the screen would be static for all time... wouldn't it?

Presumably they're making the leap that this printing technology can be leveraged to develop an alternative display technology that would change the structure in real time, kind of like color e-ink displays.

It's quite the leap, but that's science communication for you!

Especially since the breakthrough was to encapsulate the colored bits to keep them from clumping.

See the image and caption at the top of the article

  Images printed with structural colour ink can be made both highly transparent to transmitted light (top) and at the same time reflect light from above in vivid colours (bottom) – two properties that are typically considered mutually exclusive
The printing on the phone is not visible when the phone display is on as the structural printing is highly transparent. When the display is off, the printing is visible because of the reflected light.

Yes, thanks; but that's neither a "smart" display nor a means to show anything but a single, static printout of "information" when the display is off.