Carbon nanotubes increase efficiency of solar cells

Iranian researchers studied the effect of using carbon nanotubes on the efficiency of two different types of solar cells.
Sorption range is limited in pigment sensitized solar cells, and the sorption coefficient of the pigment and the lifetime of carriers are low. Solar cells based on quantum dots with adjustable sorption range and high sorption coefficient have been proposed to overcome the problem. The short lifetime of carriers also creates many problems in these types of solar cells.
The aim of the research was to modify electron transfer in solar cells to increase its efficiency. To this end, carbon nanotubes with different diameters were placed inside two types of nanostructured pigment sensitized and quantum dots solar cells. Then, the performance of the cells were studied and compared.
The research resulted in the better understanding of the performance of the two types of the cells and it distinguished their differences. Based on the results, adding carbon nanotubes in both types of cells increases the efficiency. However, the modification in efficiency is much more noticeable in quantum dots sensitized solar cells.
The structures of pigment and quantum dots sensitized solar cells are seemingly very similar. However, they have very different performance conditions. In other words, although pigment-based solar cells have higher efficiency than quantum dots-based ones, more than 40% increase in the efficiency was observed in quantum dots cells after the addition of carbon nanotubes. The increase in the efficiency was only 8% in pigment cells.
Results of the research have been published in Ceramics International, vol. 41, issue 1, 2014, pp. 497-504.