Popcorn solar cell promises to slash panel costs

Design breakthrough trebles efficiency of Zinc Oxide solar cells, boffins say new dye sensitised approach could slash costs

Researchers at the University of Washington have developed an enhanced nanotechology-based manufacturing method that could slash the cost of solar panels.

The technique uses dye-sensitised materials to generate the photoelectrons in the solar cell, as opposed to silicon which is used as the photoelectron source in more conventional cells.

"Dye-sensitised cells are much cheaper," said Guozhong Cao, who led the research team, who claims that they can cost a fifth as much as a conventional solar cell. "The downside is that the efficiencies are much lower," he added.

Traditionally, dye-sensitised cells using zinc oxide material has only boasted two per cent conversion efficiency, but Cao's team claims a six per cent efficiency using its new technique.

The team initially increased the amount of light absorbed in the solar cell by using tiny grains of zinc oxide to increase the available surface area. But it then found that by clumping these 15 nanometre grains together into popcorn-style balls 300 nanometres across, the researchers further increased the amount of light reflected inside the cell's material.

These balls of zinc oxide grains have been optimally sized to bounce light around in the gaps between each other rather than reflecting it back from the surface of the solar cell.

Cao's team worked with zinc oxide rather than the more efficient titanium oxide dye-sensitised materials because it was easier to manipulate.

Dye-sensitised solar materials using titanium oxide can get 11 per cent efficiencies, he said. That's still below the average efficiency of 15 to 16 per cent efficiency achievable with crystalline solar cells, but he hopes that applying his team's techniques to titanium oxide could increase its current efficiency by half again.

Cao said he hopes to announce results applying his team's techniques to titanium oxide in the next nine months.