Faculty Sponsor's Department:
The efficiency of organic solar cells is currently around 9%; this is low compared to inorganic cells that can exceed 40%. Compared to more traditional inorganic solar cells, organic solar cells have the advantage of low costs to manufacture large volumes. They can also be used in more flexible applications, which is useful for the expanding electronics market. Our goal was to study the properties of organic solar cells in order to increase the efficiency to a more useful level. We made solar cells with varying thicknesses and measured their internal quantum efficiency (IQE) by measuring current at different wavelengths. The active layer was composed of the most common donor and acceptor blend. We constructed four different thicknesses of solar cells varying from 200nm to 700nm thick using spin coating. Graphs of wavelength versus IQE were studied to learn more about the relative efficiencies of the donor and acceptor and the differences between the different thicknesses. We obtained information about exciton generation and conversion to free charges. This study provides important information that will enable the continued improvement of organic solar cells. Future work will involve studying these properties with different donor and acceptor blends to improve their efficiency. This will result in their wider use on the path towards renewable energy.