Semiconductor Nanomaterial Development For Photovoltaic And Thermoelectric Applications

Chen, Liangliang, Ph.D., Purdue University, December 2013. Semiconductor Nanomaterial Development for Photovoltaic and Thermoelectric Applications. Major Professor: Xiulin Ruan, School of Mechanical Engineering. Today’s world is frequently going through fossil energy shortage and environmental consequences brought by the over-emission of greenhouse gas from burning fossil fuels. Therefore, it is urgent now more than ever to discover or develop clean and sustainable power generation approaches. Among various approaches, photovoltaics and thermoelectrics have been more and more attentive both in academia and industry. Photovoltaic power generators can significantly decrease carbon dioxide emission by directly converting sunlight into electricity, and thermoelectric power generators can increase energy use efficiency by recycling waste heat into electricity. This research seeks to gain a better understanding of the mechanism that influences the energy conversion process in photovoltaic and thermoelectric materials and meanwhile use nanoengineering approaches to improve the performance of thermoelectric materials. For photovoltaic nanomaterials, we have first made progress in simulations of electronphonon coupling, which is a major mechanism for efficiency loss, in CdSe quantum dots. Time-domain non-adiabatic ab initio simulations have been performed to study the phonon-assisted hot electron relaxation dynamics in CdSe nanocrystals. It is found that