The thermoelectric properties of III-nitride materials are of interest due to their potential use for high temperature power generation applications and the increasing commercial importance of the material system; however, the very large parameter space of different alloy compositions, carrier densities, and range of operating temperatures makes a complete experimental exploration of this material system difficult. In order to predict thermoelectric performances and identify the most promising compositions and carrier densities, the thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN are modeled. The Boltzmann transport equation is used to calculate the Seebeck coefficient, electrical conductivity, and the electron component of thermal conductivity. Scattering mechanisms considered for electronic properties include ionized impurity, alloy potential, polar optical phonon, deformation potential, piezoelectric, and charged dislocation scattering. The Callaway model is used to calculate the phonon component of thermal conductivity with Normal, Umklapp, mass defect, and dislocation scattering mechanisms included. Thermal and electrical results are combined to calculate ZT values. InxGa1−xN is identified as the most promising of the three ternary alloys investigated, with a calculated ZT of 0.85 at 1200 K for In0.1Ga0.9N at an optimized carrier density. AlxGa1−xN is predicted to have a ZT of 0.57 at 1200 K under optimized composition and carrier density. InxAl1−xN is predicted to have a ZT of 0.33 at 1200 K at optimized composition and carrier density. Calculated Seebeck coefficients, electrical conductivities, thermal conductivities, and ZTs are compared with experimental data where such data are available.

Manipulating the photophysical properties of light-absorbing units is a crucial element in the design of biomimetic light-harvesting systems. Using a highly tunable synthetic platform combined with transient absorption and time-resolved fluorescence measurements and molecular dynamics simulations, we interrogate isolated chromophores covalently linked to different positions in the interior of the hydrated nanoscale cavity of a supramolecular protein assembly. We find that, following photoexcitation, the time scales over which these chromophores are solvated, undergo conformational rearrangements, and return to the ground state are highly sensitive to their position within this cavity and are significantly slower than in a bulk aqueous solution. Molecular dynamics simulations reveal the hindered translations and rotations of water molecules within the protein cavity with spatial specificity. The results presented herein show that fully hydrated nanoscale protein cavities are a promising way to mimic the tight protein pockets found in natural light-harvesting complexes. We also show that the interplay between protein, solvent, and chromophores can be used to substantially tune the relaxation processes within artificial light-harvesting assemblies in order to significantly improve the yield of interchromophore energy transfer and extend the range of excitation transport. Our observations have implications for other important, similarly sized bioinspired materials, such as nanoreactors and biocompatible targeted delivery agents.