Thermoelectric materials can convert two of the most widely used forms of energy, heat and electricity, into each other:
By converting electric energy into heat energy, solid refrigeration and temperature control can be realized. Thermoelectric materials have been used in small refrigerators, wine cabinets, high power laser temperature control equipment, and is also expected to be used in the future communication technology temperature control.
The heat energy is converted into electric energy, and the temperature difference generation can be realized. With the development of Internet of things, miniaturized thermoelectric generator is expected to become a new portable or self-powered power source.
Among all thermoelectric materials, bismuth telluride thermoelectric materials are the most widely used. It has excellent thermoelectric properties and best performance at lower temperatures near room temperature.
Recently, Professor Jingfeng Li and his team from School of Materials, Tsinghua University published an opinion article in National Science Review (NSR), analyzing the performance advantages of bismuth telluride thermoelectric materials, summarizing the research progress in the past 10 years, and pointing out the reasons for the slow performance improvement of N-type Bismuth telluride materials and their countermeasures. It provides ideas for further research and application.
In recent years, the emergence of new technologies and new theories has promoted the rapid development of thermoelectric materials, and many new thermoelectric materials with high performance have emerged. In particular, the thermoelectric optimal value (ZT) of medium and high temperature materials has been significantly improved. However, bismuth telluride thermoelectric materials are still the only commercial thermoelectric materials that have achieved large-scale application, and also the thermoelectric materials with the best performance near room temperature.
In the past decade, based on energy band engineering, dislocation engineering, defect engineering and other means, p-type Bismuth telluride materials have made breakthroughs, and their peak ZT value has reached 1.4-1.6. However, the optimization of n-type Bismuth telluride thermoelectric materials based on the same idea has not achieved significant progress, and the peak ZT corresponding temperature is also significantly higher than room temperature
N-type and P-type Bismuth telluride thermoelectric materials with ZT value >1 in recent 10 years
In view of this situation, starting from the crystal structure of Bismuth telluride material, this paper analyzes the differences of band structure and electric transport characteristics between P-type and N-type Bismuth telluride materials (figure A-D), and points out that future research and exploration should focus on:
To develop new material preparation processes to improve the performance of N-type Bismuth telluride thermoelectric materials;
Nanocomposite structures and texturized micro-nano structures were designed and fabricated.