Efficiency Enhancement of Cadmium Telluride Solar Cells via Nanoengineering

CdTe solar cells are one of the most promising candidates for photovoltaic applications from an economical perspective due to their decent optical and electrical characteristics combined with the relatively inexpensive fabrication processes. The development of CdTe cells started in 1972 with the introduction of a 6% efficient device and was improved progressively until 2002 when the record efficiency was set to around 16.7%. Even though the theoretical efficiency limit for this kind of photovoltaics is around 30%, there have not been any performance improvements of CdTe cells over the last decade. This work explores nontraditional, nanoengineering approaches to improve performance of CdTe cells. A nanocrystaline layer composed of self-assembled quantum dots has been inserted into the standard CdTe device structure to examine potential mechanisms for the efficiency enhancement such as Plasmonic effect, Photon Energy Conversion, Multiple Exciton Generation, and Fluorescence Resonant Energy Transfer. However, fabrication of the devices with the nanocrystalline layer proved difficult due to adhesion problems induced by higher temperature processes associated with the fabrication procedure. In this context, specific issues have been indentified and further steps have been suggested. As an example, block copolymer lithography has been considered as an approach to obtain highly ordered nanostructures of metal nanoparticles, expected to be more robust in comparison.