Human hair used to produce cheaper cathodes for solar cells

•  Researchers at the Indian Institute of Science Education and Research (IISER) in Kolkata have used human hair to produce cost-effective, metal-free cathodes for use in solar cells.
• While metal-free cathodes produced in the past have not performed as well as the traditional metal-based ones, but the performance of graphitic porous carbon cathode produced by IISER, has been at par with metal-based cathodes.
• This is the first instance where a bio-waste-derived electrode has been used as cathode in a quantum dot sensitised solar cell device.
• Producing graphitic porous carbon cathode using human hair is simple, quick and inexpensive. Unlike in the case of other synthetic porous carbons, no physical or chemical activation process or templates are required to produce the pores of 2-50 nm diameter.
• The porosity, along with high surface area to volume ratio, plays an important role in adsorption-desorption of electrolyte.
• The cleaned and dry human hair is first treated with sulphuric acid at 165 degrees C for 25 minutes to achieve precarbonisation. It is then heated to different temperatures in the presence of an inert gas for six hours to carbonise and bring better electrical conductivity for efficient charge transfer.

Benefits:

• The cathode shows an impressive performance in converting visible sunlight to electricity much higher than commercially available activated carbon cathodes and is comparable with commonly used cathodes made of platinum metal and metal sulfides.
• Besides its higher efficiency to convert visible sunlight to electricity, the cathode was found to generate high open-circuit voltage, which is at par with conventional platinum and activated carbon cathodes. Thereby, the power conversion efficiencies can also be enhanced.
• They also have the potential to bring down the cost of solar cells.

By: Vishal