Development and understanding of solvothermal synthesized copper chalcogenide thermoelectric materials

Abstract

Thermoelectric materials, with the capacity of direct energy conversion between heat and electricity, are attracting ever-growing research interest. Traditional thermoelectric materials, such as Bi2Te3 and PbTe, contain earth-rare or highly toxic element. Hence, recent studies in thermoelectrics are focusing developing new eco-friendly and low-cost thermoelectric materials. Phonon-liquid electron-crystal Cu2X-based thermoelectric are attracting extensive research interest due to relatively high performance. Solvothermal-synthesized highly crystallized Cu2X-based thermoelectric are acquiring attention due to low lattice thermal conductivity which should be mainly attributed to the nano-sized grains induced dense grain boundaries. Triggered by the idea that point defects can effectively scatter phonons in traditional thermoelectric materials, leading to low lattice thermal conductivity and enhance the thermoelectric performance, in this thesis, the influence of Ag doping on thermoelectric performance of Cu2Se were firstly studied. The abnormally enhanced lattice thermal 'Life was like a box of chocolates. You never know what you are goanna get.'-Forrest Gump. Supervisors are more than supervisors. The luckiest thing for a PhD student is coming up with a good supervisor, not to mention two. It is a great honour and of great fortune to have both Jin and Zhi-Gang as my supervisors. First thing first, I would like to express sincere gratitude to Prof. Jin Zou and Prof. Zhi-Gang Chen. Without their confidence on me, I can not have this opportunity studying here and change everything. In my first two year, without any valuable results, it is their encouragement that keeps me pushing forward and finally made the achievements. Jin enlightened me with his extensive knowledge and prudent attitude, and taught me about the role of an honourable researcher. Zhi-Gang impressed me with the scientific thinking and understanding, which is the key for looking for scientific fact lying behind the messy data. Most importantly, both Jin and Zhi-Gang are kind, helpful, of empathy and are always thinking for the goodness of the students. Secondly, I would like to thank my colleagues. Prof. Lei Yang and Dr Min Hong, who rendered systematic training on the experiments.