The intense interest in harvesting energy from heat sources has led to a renewed push to discover materials that can more efficiently convert heat into electricity. Some researchers are finding those gains by re-designing materials scientists have been working with for years.
While long valued for high-temperature applications, the bulk alloy semiconductor SiGe hasn't lent itself to broader adoption because of its low thermoelectric performance and the high cost of Germanium. A novel nanotechnology design created by researchers from Boston College and MIT has shown a 30 to 40 percent increase in thermoelectric performance and reduced the amount of costly Germanium. Credit: Nano Letters
A team of Boston College and MIT researchers report developing a novel, nanotech design that boosts the thermoelectric performance of a bulk alloy semiconductor by 30 to 40 percent above its previously achieved figure of merit, the measuring stick of conversion efficiency in thermoelectrics.
The alloy in question, Silicon Germanium, has been valued for its performance in high-temperature thermoelectric applications, including its use in radioisotope thermoelectric generators on NASA flight missions. But broader applications have been limited because of its low thermoelectric performance and the high cost of Germanium.
Boston College Professor of Physics Zhifeng Ren and graduate researcher Bo Yu, and MIT Professors Gang Chen and Mildred S. Dresselhause and post-doctoral researcher Mona Zebarjadi, report in the journal Nano Letters that altering the design of bulk SiGe with a process borrowed from the thin-film semiconductor industry helped produce a more than 50 percent increase in electrical conductivity.
The process, known as a 3D modulation-doping strategy, succeeded in creating a solid-state device that achieved a simultaneous reduction in the thermal conductivity, which combined with conductivity gains to provide a high figure of merit value of ~1.3 at 900 °C.
"To improve a material's figure of merit is extremely challenging because all the internal parameters are closely related to each other," said Yu. "Once you change one factor, the others may most likely change, leading to no net improvement. As a result, a more popular trend in this field of study is to look into new opportunities, or new material systems. Our study proved that opportunities are still there for the existing materials, if one could work smartly enough to find some alternative material designs."
Ren pointed out that the performance gains the team reported compete with the state-of-the-art n-type SiGe alloy materials, with a crucial difference that the team's design requires the use of 30 percent less Germanium, which poses a challenge to energy research because of its high cost. Lowering costs is crucial to new clean energy technologies, he noted.
"Using 30 percent less Germanium is a significant advantage to cut down the fabrication costs," said Ren. "We want all the materials we are studying in the group to help remove cost barriers. This is one of our goals for everyday research."
The collaboration between Ren and MIT's Chen has produced several breakthroughs in thermoelectric science, particularly in controlling phonon transport in bulk thermoelectric composite materials. The team's research is funded by the Solid State Solar Thermal Energy Conversion Center.
The 3STEC Center is part of the U.S. Department of Energy's Energy Frontier Research Center program, which is aimed at advancing fundamental science and developing materials to harness heat from the sun and convert the heat into electricity via solid-state thermoelectric and thermophotovoltaic technologies.
Ed Hayward | EurekAlert!
Researchers use light to remotely control curvature of plastics
23.03.2017 | North Carolina State University
TU Graz researchers show that enzyme function inhibits battery ageing
21.03.2017 | Technische Universität Graz
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy