Building functional Materials from the nanoscale up
My group uses functional imaging to enhance materials design and synthesis. In this seminar I will present three recent projects. In the first project, we assemble nanoparticles at the interface of immiscible liquids by strongly binding them to surfactant molecules. These assemblies form stiff films that stabilize the interface and allow us to create persistent liquid in liquid structures that can be used as reconfigurable microfluidics, reaction vessels, and even liquid ferromagnets. We also discovered that this system shows anomalous emulsion phase inversion behavior and we use nanoscale in-situ imaging to provide a detailed physical explanation. In the second project, we characterize the factors that limit energy conversion efficiency in CIGS photovoltaic devices. Using high resolution Kelvin Probe Force Microscopy, we identified regions of electron accumulation near the P-N junction where a 100mV barrier reduces the open circuit voltage of the device. We also characterized deep negatively charged hole traps throughout the active layer as a source of recombination. In the third project, we are creating bacterial tissue. We modify the genome of a fresh water bacterium C. Crescentus to express S-layer protein displaying a spy-tag motif. We use spycatcher functionalized nanoparticles to assemble the cells into a stiff tissue with very different mechanical properties than typical biofilms due to their tight specific crosslinkers.