Honeycomb design could enhance thin-film solar cells

A new honeycomb design for thin-film solar cells could reduce the amount of silicon needed to produce them and boost efficiency.

The design uses a 3D nanostructure to improve the absorption of light into solar cells made from special forms of silicon known as amorphous and microcrystalline, which can be produced in high yields for low costs.

Previously, these types of thin-film solar cells have been less efficient than the dominant types, which use crystalline wafer-based silicon.

A team from Swiss firm Oerlikon Solar and the Institute of Physics’ photovoltaic group at the Academy of Sciences of the Czech Republic conducted the research.

‘To make amorphous and microcrystalline silicon cells more stable, they’re required to be very thin because of tight spacing between electrical contacts, and the resulting optical absorption isn’t sufficient,’ said Milan Vanecek, head of the photovoltaic group.

The team’s new design focuses on optically thick cells that are strongly absorbing, while the distance between the electrodes remains very tight.

Honeycomb solar cell

The cells are created by depositing the silicon on a nanostructured substrate of zinc oxide nanocolumns, or on a honeycomb array of micro- or nano-holes etched into a transparent conductive oxide layer.

‘Our new 3D design of solar cells relies on the mature, robust absorber deposition technology of plasma-enhanced chemical vapour deposition, which is a technology already used for amorphous silicon-based electronics produced for liquid-crystal displays,’ said Vanecek.

‘The potential of these efficiencies is estimated within the range of present multicrystalline wafer solar cells, which dominate solar-cell industrial production.

‘And the significantly lower cost of Micromorph panels, with the same panel efficiency as multicrystalline silicon panels [12 to 16 per cent], could boost its industrial-scale production.’