Germanium Nanoparticle Films for Thermoelectrics
Ben Zhou
Mentor: Allon Hochbaum
Modern energy needs demand novel methods of energy generation. Thermoelectric materials, which generate
electricity directly from heat, can be used to scavenge waste heat, improving the efficiency of our use of
energy resources. Germanium and silicon are desirable materials for thermoelectrics because of their
abundance and processability. While poor thermoelectrics at the bulk scale, nanoscale effects can greatly
improve their performance. Germanium nanoparticles created through solution based synthesis can be
functionalized with various ligands which can also alter their thermoelectric performance. In this project,
germanium nanoparticles with several different ligands were processed with different solvents and deposition
conditions to form continuous, densely packed films which can be used for testing. The first experiments
were conducted with hydride terminated particles; it was found that the reactivity of their surfaces resulted in
a porous structure that could not be densified by processing. Using oleylamine terminated particles instead,
films with no visible porosity at up to 100,000x magnification were deposited. For all ligands tested,
evaporative assembly resulted in the most uniform, dense films, over standard techniques like drop casting or
spin coating.