Chemical Engineering Seminar
Self-assembly and crystallization from solutions, melts, or solids involve complicated thermodynamic, kinetic, and mass transport effects that are challenging to elucidate and control, even more so in the presence of functional solute species. Such processes are central to the syntheses and resulting properties of diverse inorganic, organic, and inorganic-organic hybrid materials, the understanding of which is often elusive because of their heterogeneous, multicomponent, and/or non-equilibrium characters. The challenges are exacerbated by the complex order and disorder that additionally result from distributions of functional species and environments or the roles of surfaces, which can have large influences on macroscopic material properties and device performances. This is the case for many light-responsive materials with promising engineering applications, such as rare-earth-doped phosphors, semiconductor nanocrystals, conjugated polymers, and block-copolymer hybrids containing photo-active guests. By using a combination of spectroscopic, scattering, and bulk property measurements, such materials can be probed over multiple length and time scales to correlate their compositions and structures with their macroscopic properties and functions. In particular, advancements in solid-state nuclear magnetic resonance spectroscopy, especially the availability of ultrahigh magnetic fields and new dynamic-nuclear-polarization-enhanced techniques, enable new insights to be obtained on the atomic-level environments, interactions, and distributions of functional species in bulk solids or near surfaces. Recent results will be presented on the measurement and influences of order and disorder on the light-responsive properties of inorganic, organic, and hybrid materials, which provide criteria to guide their rational design for solid-state lighting, photovoltaic, or electrochemical device applications.