Unique coral-shaped nanomaterials could improve the efficiency of solar cells, say Chinese scientists. 

Porous materials, such as tin oxide, have properties that make them ideal for use in solar cells, batteries, gas sensors and other devices. Changing their structure and morphology can enhance their properties, but this can be difficult to control using current preparation methods, says Jinhuai Liu at the Chinese Academy of Sciences, Hefei. 

The coral-shaped nanomaterials have higher surface area than spherical ones

Liu and his colleagues have made tin oxide nanomaterials shaped like coral. They found that the high surface area and long term stability improved the efficiency of dye-sensitised solar cells (DSSCs) compared with spherical shaped nanoparticles. 

Liu's nanoshapes are made via a 'swallowing growth mechanism'. Whereby, nanospheres made using a hydrothermal reaction stick together and aggregate into one parent structure when the reaction time is extended. This process continues, with the parent structure 'swallowing' and assimilating nanospheres until a coral-shaped structure with many radial tentacles is formed. 

'[The unique coral shape] is of great significance for developing new-types of DSSCs' says Liu. 'The demonstrated novel process creates new opportunities for designing other functional nanomaterials with specific structures for applications ranging from lithium-ion batteries and sensors to catalysts,' he adds. 

The group now intend to look at other applications of the coral-shaped tin oxide and to use their process to produce other tin oxide shapes. 

Harriet Brewerton 

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