There are two well-known modes of operations for thermoelectric modules: power generation and refrigeration. Thermoelectric modules can convert heat directly into electricity and therefore are proposed for waste heat recovery. Like most other heat engines, they can also operate in the refrigeration mode where work is performed to pump heat from the cold side to the hot side. In this talk I will discuss additional operational modes of the thermoelectric modules including active cooling wherein the modules are used as heat spreaders and thermal switching mode wherein the modules are used as variable thermal resistors. Materials properties needed for each mode of operation will be discussed with some strategies to improve the thermoelectric performance in several classes of materials. In particular, I will highlight semimetals and hybrid organic- inorganic materials as two classes of materials that could be potentially useful for thermoelectric applications. Mona Zebarjadi is a joint professor of Electrical and Computer Engineering and Materials Science and Engineering Departments at University of Virginia, where she is leading the Energy Science and Nanotechnology Lab (ESNL). Prior to her current appointment she was a professor of Mechanical Engineering Department at Rutgers University. Her research interests are in electron and phonon transport modeling; materials and device design, fabrication and characterization; with emphasis on energy conversion systems such as thermoelectric, thermionic, and thermomagnetic power generators, and heat management in high power electronics and optoelectronic devices. She received her Bachelor's and master's degree in physics from Sharif University and her PhD in EE from UCSC in 2009, after which she spent 3 years at MIT as a postdoctoral fellow working jointly with electrical and mechanical engineering departments. She is the recipient of 2017 NSF Career award, 2014 AFOSR career award, 2015 A.W. Tyson assistant professorship award, MRS graduate student gold medal, and SWE electronics for imaging scholarship.