Innovations Report

Growing – and precisely aligning – microscopic, spear-shaped zinc oxide crystals on a surface of single-crystal silicon, researchers at Missouri University of Science and Technology may have developed a method to make more efficient solar cells.

Dr. Jay A. Switzer and his colleagues at Missouri S&T report in the journal Chemistry of Materials that their simple, inexpensive process could also lead to new materials for ultraviolet lasers, solid-state lighting and piezoelectric devices.

“It’s kind of like growing rock candy crystals on a string,” says Switzer, the Donald L. Castleman/Foundation for Chemical Research Professor of Discovery at Missouri S&T. But instead of using sugar water and string, Switzer’s team grows the zinc oxide “nanospears” on the single-crystal silicon placed in a beaker filled with an alkaline solution saturated with zinc ions. The process yields tilted, single-crystal, spear-shaped rods that grow out of the silicon surface, like tiny spikes.

The spears are about 100-200 nanometers in diameter – hundreds of times smaller than the width of a human hair – and about 1 micrometer in length. A nanometer – visible only with the aid of a high-power electron microscope – is one billionth of a meter, and some nanomaterials are only a few atoms in size.

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