Like a hall of mirrors, nanostructures trap photons inside ultrathin solar cells

PUBLIC RELEASE DATE:

22-Apr-2014

Contact: Tom Abate tabate@stanford.edu 650-736-2245 Stanford School of Engineering

In the quest to make sun power more competitive, researchers are designing ultrathin solar cells that cut material costs. At the same time they're keeping these thin cells efficient by sculpting their surfaces with photovoltaic nanostructures that behave like a molecular hall of mirrors.

"We want to make sure light spends more quality time inside a solar cell," said Mark Brongersma, a professor of materials science and engineering at Stanford and co-author of a review article in Nature Materials.

Brongersma and two Stanford colleagues -- associate professor of materials science and engineering Yi Cui and professor of electrical engineering Shanhui Fan -- surveyed 109 recent scientific papers from teams around the world.

Their overview revolves around a basic theme: looking at the many different ways that researchers are trying to maximize the collisions between photons and electrons in the thinnest possible layers of photovoltaic materials. The goal is to reveal trends and best practices that will help drive developments in the field.

Solar energy is produced when photons of light collide with the electrons in a photovoltaic crystal. As loose electrons move through the crystal, they generate an electrical current.

Today's solar cells are already thin. They are made up of layers of photovoltaic materials, generally silicon, that average 150 to 300 micrometers, which is roughly the diameter of two to three human hairs.

As engineers continue to shave down those dimensions they have to develop new molecular traps and snares to ensure that photons don't simply whiz through their ultrathin solar cells before the electrical sparks can fly.

Read the original:
Like a hall of mirrors, nanostructures trap photons inside ultrathin solar cells