Solar absorber holds promise for next-gen solar cells

A new type of solar thermal absorber could help usher in next generation high-efficiency solar cells, researchers have claimed.

Developed by engineers at the Universities of Bristol and Exeter the technology uses amorphous carbon as an inter-layer between thin gold films, with the upper film patterned with a 2D periodic array using focused ion beam etching.

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The focused ion beam fabricated trilayer metasurface within the inset shows rounded features in the upper 2-D gold square periodic surface.

It is claimed to be one of the world’s first examples of a tri-layer metasurface absorber using a carbon interlayer.

The trilayer gold-carbon-gold metasurface strongly absorbs light across the solar spectrum but minimises emission of thermal radiation from the structure.

The group claims that the use of gold in the research is a first step towards a high temperature metasurface where gold can be replaced by other refractory metals such as tungsten or chrome.

The cell will be used for solar thermal energy applications and has the potential to reach much higher temperatures than simple black surfaces because it can minimise the emission of thermal radiation.

The ultimate aim of the project is to develop diamond-based solar thermionic devices, which use sunlight to get surfaces sufficiently hot that they emit electrons directly into a vacuum. If these electrons are collected at a cooled anode, electrical energy can be produced with maximum efficiencies predicted to be much higher than is achievable using conventional silicon solar cells.