Remember those solar-powered calculators from your youth? The ones you could take out of your backpack, and it always “just worked?”

This article brought back those memories and got me wondering: why don’t I see those anymore? Why didn’t solar-powered gadgets catch on?

Chris Mims, an incredible tech columnist at the Wall Street Journal (and, many years ago, my former colleague at MIT Technology Review!), has the answers.

Turns out, those calculators were just the tip of a solar-powered iceberg that never quite broke the surface. Back then, indoor light was like a technological desert for solar cells, barely squeezing out enough juice to power a basic calculator, let alone our smartphone-hungry lives.

Well, the game has changed. A new generation of solar cells, known as a “dye-sensitized solar cell,” are lightweight, bendable, cheap to manufacture, and ready to revolutionize how we power our gadgets.

By mimicking photosynthesis in plants, these flexible sheets let headphones charge under a windowsill, keyboards ditch the cable forever, electronic door locks never need a battery change, and even remote controls come back to life after a quick sunbath.

Hopefully, soon, we will be taking our phones out of our pockets and not even looking at how much charge it has left.