It’s a trap—Researchers identify the process by which…

It’s a trap—Researchers identify the process by which holes get trapped in ZnO nanoparticles

When a solar cell absorbs a photon of light, it starts an electronic race against time. Two particles—a negatively charged electron and positively charged “hole”—generate electricity if they fully separate.

However, when these particles become trapped within a solar material before they can fully separate, it can diminish the ability of the material to convert light into electricity.

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have published a new study that identifies the process by which holes get trapped in nanoparticles made of zinc oxide, a material of potential interest for solar applications because it absorbs ultraviolet light.

“If you are making a solar cell, you want to avoid trapping holes; but if you’re making a photocatalyst, you want to trap them.”—X-ray scientist Christopher Milne of Switzerland’s Paul Scherrer Institute.

Using X-rays produced by Argonne’s Advanced Photon Source (APS), the researchers were able to see the trapping of holes in specific regions of the nanoparticle. This represents a notable advance, as previous experiments were able to detect the migration and trapping of electrons but not holes.

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