Surface Plasmon Enhanced Quantum Dot Solar Cells

As the domestic economic growth and the soaring demands of energy, development of clean and renewable energy is extremely urgent. It is commonly believed that production and activities brought about by human beings deteriorate our environment. However, quantum dot solar cells(QDSCs) and plasmonic solar cell have attracted considerable attention since last few decades. QDSCs has a potential to break through the theoretic maximum convertion efficiency of traditional p-n junction solar cells, reaching 66% conversion efficiency. Meanwhile, plasmonics technologies are applied on solar cells to reduce the materials used in solar cell fabrication, lowering the price down. As a result, it is competitive with fossil-fuel technologies. If we achieve efficient low-cost solar cell, not only can we reduce the reliance on traditional fossil energy, but also to achieve sustainable economic development strategy of the country. The dissertation investigates the surface plasmon on the QDSCs by coupling nanostars on GaAs solar cell surface in a facile method, boosting efficiency considerably. The multispiked nanostars provide broadband scattering and absorption cross-sections, which can be engineered to dramatically boost the performance of the solar cells. The localized near field modes of nanostars result in an external quantum efficiency enhancement over 400% for short-wavelength light absorbed in the emitter, while plasmon light trapping causes distinct improvement in quantum efficiency(10-50%) in the long-wavelength region up to 1100 nm. To verify the influence of plasmonic source on InAs quantum dots(QDs) in intrinsic region, it was etched to make the nanostars close to QDs. Finite difference time domain method is adopted to explain the origin of the optical absorption enhancement in the quantum dot solar cells. The broadband light concentration by plasmonic nanostars can significantly reduce the amount of quantum dot materials required for a solar cell and provide efficient utilization of the full solar spectrum. Therefore, the surface plasmonic QDSCs has the potential to reduce materials for solar cells and cut down the price of solar cells, providing a new methodology to address the energy crisis all over the world.