Press Release

The key to low-cost solar cells: Is it thinner than a human hair?

While thin film technologies are receiving worldwide attention with their potential to lower the cost of solar energy, there are researchers who are thinking outside the box and are looking into different approaches that will result in cost reductions for photovoltaic technologies.

One of those approaches comes with the collaboration of the Department of Engineering Physics at McMaster University, Cleanfield Energy and the Ontario Centers of Excellence (OCE), which have formed a partnership to pursue the commercialization of nanowire technology in the production of solar cells.

'One of the biggest obstacles to widespread use of solar cells as a clean source of energy is cost,' said Ray LaPierre, assistant professor of engineering physics at McMaster University and project leader for the collaboration. 'Our work with nanowire fabrication at this stage shows the potential for greater energy efficiency with less costly materials.'

Semiconducting nanowires (e.g., Si, InP, GaN, etc) exhibit aspect ratios (length-to-width ratio) of 1000 or more. As such they are often referred to as one-dimensional structures with controlled lengths of one to five microns and diameters of 10 to 100 nanometres (thousands of times thinner than a human hair). Some of the advantages they offer over thin film and crystalline silicon technologies (both currently used in solar cell production) include:

•low material utilization
•use of low-cost substrates
•defect-free materials with high conversion efficiency
•strong light trapping and absorption

The exceptional properties of nanowires that are not seen in bulk or 3-D materials are due to the lateral quantum confinement of electrons. Nanowires are excellent at trapping light, very efficient at absorbing the sun's energy and allow for greater electrical output per unit surface area.