CAREER: Fundamental Understanding of Thermal Transport at the Single Molecule Level

Understanding and control of matter, energy, and information at the nanoscale is one of major hallmarks of modern engineering and sciences. Atomic and single-molecule devices represent the miniaturization limit of any physical machine, and have great potential to create unprecedented functionalities that overcome the performance barriers set by classical physical laws. Directly probing heat transport at the molecular scale will elucidate the fundamental thermal transport mechanisms and dissipation limits in these ultraminiaturized devices, but has remained as a great technological challenge. The principal aim of this project is to fill the knowledge gap in the understanding of thermal transport at the single molecule level. The outcomes of this project can potentially transform the current technologies of energy efficient nanoelectronics and photonics, as well as enable rational bottom-up design methods of high performance thermal and renewable energy materials. This project also focuses on training and diversifying the pool of young generations of nano-engineers and thermal scientists through an integrated education and outreach program that promotes the engagement of K-12 and undergraduate students, particularly those from underrepresented groups, in cutting-edge lab research, workshops, and hands-on learning. The goal of this project is to establish a comprehensive research framework for the fundamental study of heat conduction and energy conversion mechanisms in single molecules. This research will enable systematic tests to address long-standing open questions in molecular thermal transport, which although having a long research history starting from the 1950s, remain at a qualitative level due to the lack of experimental benchmarking data. This project leverages a recently developed scanning thermal microscope with ultrahigh sensitivity that allows the discovery of new thermal effects and promotes creative design of organic molecules from a thermal perspective. Experimental studies will be performed in a series of molecular systems with specific aims to reveal the structure-property relationships in thermal transport of single organic monomers and polymers, and to quantify quantum effects and the figure of merit of thermoelectric molecules. This research is expected to yield deep understanding in molecular phononics and quantum thermoelectrics, and profoundly impact the field of heat management, molecular electronics, and the material design of thermally-enhanced polymers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.