TITLE : Nanostructured Thermoelectric Energy Conversion

ABSTRACT :

With about 2/3 of all utilized energy being lost as heat. Thermoelectric materials can convert waste heat to electrical energy, and it will have a significant role in future energy management. One of the fundamental challenges in developing high-performance thermoelectric materials has been to achieve low lattice thermal conductivity (κ L ) but simultaneously enhancing the electrical transport. Nanoprecipitates of the size 1-20 nm embedded in bulk matrix are extraordinary to scatter the heat carrying acoustic phonon which decreases the κ L and increases the thermoelectric figure of merit (zT). Formation of layered intergrowth nanostructures in SnTe matrix or in the form of 2D heterostructure nanosheets by kinetic synthesis can lead to ultralow κ L . 1, 2 2D layered nanostructures such as in the case of SnSe are superior in decreasing thermal conductivity than that of the traditional spherical nanoprecipitates. 3 These nanostructures decrease κ L significantly but affect electrical transport. Thereby, a leap in performance requires innovative strategies that simultaneously optimize electronic and phonon transports. Recently, we demonstrated extremely high thermoelectric performance (zT ~2.6 at 573 K) by optimizing atomic disorder in polycrystalline AgSbTe 2 via Cd doping. Cd doping in AgSbTe 2 enhances cationic ordering, which simultaneously improves the electronic properties by tuning disorder-induced localization of electronic states and reduces κ L via spontaneous formation of nanoscale (~2-4 nm) superstructures and coupling of soft vibrations localized within ~1 nm around Cd sites with local strain modulation. 4 The strategy is applicable to most of other thermoelectric materials which exhibit inherent atomic disorder.

MEETING DETAILS :

Speaker: Prof. Kanishka Biswas

Venue: Online

Date and Time: March 18th, 2022, 5 pm