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The most abundant source of renewable energy is the sun, which can be converted directly to useful forms of energy such as electricity by photovoltaics. Intensive research has been carried out over the past several years both to improve the efficiency and reduce the cost of solar cell devices. One device structure that has attracted much recent interest is that of the quantum dot solar cell, which has the potential for achieving low cost, high efficiency conversion of solar energy to electricity. The simplicity of the room-temperature fabrication process and the robustness of the devices to ambient conditions provide advantages compared with other solution-processed solar cells. However, quantum dot solar cells are currently limited by the recombination of excited electrons and holes inside the solar cell resulting in low fill factors and photovoltages.
In the first half of my talk, I will be discussing a strategy to boost photovoltaic performances of quantum dot solar cells by doping Mn2+into the quantum dots, which helps in reducing recombination due to long lived spin and orbital forbidden d-d transitions in Mn2+. In the second part, I will explain how band engineering of quantum dots can be employed to enhance the directionality and charge carrier collection and overall photovoltaic performances of this type of devices.
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