Thermoelectric devices cleanly convert heat into electricity and play an important role in satisfying the future global demand for efficient energy management. However, there exists a significant barrier to improving thermoelectric devices and that is the thermoelectric materials themselves. The most promising candidate materials are (heavily doped) narrow-gap semiconductors with low thermal conductivity. While crystal chemical mechanisms have been identified for reducing the thermal conductivity, a rationale selection of compositions and structures leading to bulk narrow-gap semiconductors is not well established. We present an international and interdisciplinary research program aimed at advancing thermoelectric materials research to uncover promising materials and provide new scientific understanding of materials that border/overlap metals and semiconductors. Taking the state-of-the-art thermoelectric Zn4Sb3 as a starting point, we conceptually integrate this material into a larger class of chemical compounds electron poor framework semiconductors (EPFSs) which includes elemental boron at one extreme. EPFS materials, made from metal and semimetal atoms, form a common, weakly polar framework containing multi-center bonded structural entities. The localized multi-center bonding feature is thought to be the key to structurally complex semiconductors. Binary and ternary EPFS materials that have so far been identified and characterized show promising thermoelectric properties; especially remarkable is their low thermal conductivity. Through a combination of chemical synthesis, structure analysis, computational modeling, and physical property measurements we explore systematically the compositional and structural potential of EPFS materials, and analyze their bonding properties and the mechanisms behind their peculiar, but desirable, low thermal conductivity. The effort will be carried out as collaborative activity among three institutions, Arizona State University (ASU, USA), Augsburg University (Germany), and Technical University Munich (Germany) assembling a research group with faculty, staff and students from Chemistry and Physics departments.
|Effective start/end date||7/15/10 → 6/30/14|
- National Science Foundation (NSF): $600,000.00