MIT team enhances dye solar cell efficiencies by almost a third

Sara Ver-Bruggen - 06 May 2011

Researchers at Massachusetts Institute of Technology (MIT) have succeeded in covering single-walled carbon nanotubes (SWCNT) with titanium dioxide to bring about higher conversion efficiencies in dye-sensitised solar cells (DSCs).

Italian energy firm ENI sponsored the initiative, led by Angela Belcher - whose work focuses on exploiting biological processes to make molecular-level composites that are yielding advances in renewable energy, cleantech and medical fields, among others.

Used to make the photoanode layer in the DSCs, the nanocomposites enabled the cells to achieve a 2.6% increase in power conversion efficiency.

For the research Belcher's team made small-scale solar cells a few centimetres in size. ENI will look to replicate the results in larger devices in the coming months.

According to Belcher: 'My group's goal is to figure out how to integrate materials from different classes together, to get better efficiency and performance from promising nanotechnologies.'

Nanocomponents

In 2010 Belcher and one of her students demonstrated how an engineered virus - M13 - supported the assembly of the nanoscale components needed to split a water molecule into hydrogen and oxygen atoms.

The same principle of using the modified virus to hold and support nanocomponents is applied to DSCs. The virus keeps the SWCNTs in place, and separate to prevent clumping. The team has also been able to demonstrate for the first time that the virus can be switched - in this case so that it can produce a titanium dioxide pocket for each nanotube, maintaining the nanotubes' stability within an aqueous solution.

The amount of virus and nanotube composite makes up less than 0.5% of the cell's weight, so scaling it up is feasible, says Belcher.

Belcher co-founded Cambrios, which is commercialising a transparent electrode film based on silver nanowires in displays, and is pursuing other photovoltaic applications.

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