Mimicking mother nature's solar panels

Scientists in China have studied the antireflective behaviour of black butterfly scales to understand the way these natural solar collectors work. The study could inspire new solar cells, anti-reflective films in lenses, micro-optical sensors and stealth technology.

The butterfly scales' blackness is a result of the combined effect of physical and chemical factors

Tongxiang Fan from Shanghai Jiaotong University and colleagues combined morphology characterisation, spectrophotometry and theoretical modelling in their investigation into the black scales of the Triodes aeacusbutterfly.

The team found that the scales' blackness is a result of the combined effect of physical and chemical factors. 'The scales' nanostructure acts as the physical element and enhances light harvesting by reducing reflection when light enters the scales. Then, the melanin pigment distributed in the bottom part of the scales chemically absorbs incident light and energy is transferred to the electrons of the melanin. The physics and chemistry mutually assist each other to give maximum light absorption, generating the ultra-black effect,' explains Fan.

'The work demonstrates another great example of how studying nature's creations can provide an insight into how to apply its engineering design rules in manmade solutions to many of today's problems,' says Daniel Hill, an expert in photonic nanoparticle-polymer nanocomposite materials from the University of Valencia, Spain. 'The gauntlet has been laid down for photonics designers to incorporate these structures into their devices and for micro and nanofabrication technologists to realise them accurately, reproducibly and at a cost suitable for mass production.'

'Nature is a great art gallery involving numerous creatures. These organisms usually exhibit extraordinary intelligence in order to live or face challenges in a harsh environment,' says Fan. 'Mimicking the basic principles of these sophisticated tactics is important for the design of artificial analogues.'

Jennifer Newton

Art of blackness in butterfly wings as natural solar collector
Qibin Zhao, Xingmei Guo, Tongxiang Fan, Jian Ding, Di Zhang and Qixin Guo, Soft Matter, 2011
DOI: 10.1039/c1sm06167d

http://www.rsc.org/chemistryworld/News/2011/October/20101102.asp