Solar collector

Researchers at Missouri University of Science and Technology have developed a method that could be used to make more efficient solar cells by growing and precisely aligning microscopic, spear-shaped zinc-oxide crystals on a surface of single-crystal silicon.

Prof Jay Switzer and his colleagues at Missouri S&T say that their simple, inexpensive process could also lead to new materials for ultraviolet lasers, solid-state lighting and piezoelectric devices.

Switzer's team grew the zinc-oxide nanospears on a single crystal of silicon placed in a beaker filled with an alkaline solution saturated with zinc ions. The process yields tilted, single-crystal, spear-shaped rods about 100-200 nanometres in diameter that grow out of the silicon surface like tiny spikes.

Zinc oxide is a semiconductor that possesses some unusual physical properties, Switzer said. The material both absorbs and emits light, so it could be used in solar cells to absorb sunlight as well as in lasers or solid-state lighting as an emitter of light.