What do high-power lasers have to do with conjugated polymers?

Nothing.

The only tenuous connection is my scientific path from PhD student in Berkeley to DDS&T at SLAC, which was heavily influenced by having access to the three Bay Area National Labs.

I will thus spend the first part of this talk describing my research in laser-induced damage in fused silica at the National Ignition Facility. Laser-induced damage in optical glass imposes one of the fundamental limitations to the fluence that can be used to achieve fusion by inertial confinement. As is often the case in materials science, it’s defects that define the performance of the material. I used tools designed to simulate optical lithography for the semiconductor industry in order to study what defects are most harmful and why. What was less expected is that one can draw meaningful parallels between laser-induced damage in glass and impact cratering by meteorites on the surface of planets and observe the formation of high-pressure phases of SiO₂.

The second part of my talk will describe my current research which involves studying a relatively new class of materials: conjugated polymers. Conjugated polymers behave as semiconductors and find applications ranging from solar cells and LEDs to neural probes and biosensors. In these applications conjugated polymers can behave as regular semiconductors or as electrochemical materials, which makes them unique. One of the selling points of these materials is that they can in principle be designed de novo to perform desired functions. Despite their enormous potential, the structure-property relationships in conjugated polymers are far from understood. This gap, that is the connection for molecular structure to microstructure, is a major impediment to the rational design of new high-performance conjugated polymers. Structure-property relationships are further complicated by the fact that these materials are “dynamic” and change their structure at different length scales as they interact with electronic or ionic charges. I will describe our work over the years in attempting to tease out structure-property relationships in conjugated polymers using optical, electrical and electrochemical characterization, synchrotron-based x-ray diffraction and transmission electron microscopy.