The motivation for, and performance of, silicon nanostructures including porous silicon in thermoelectrics is reviewed. A high thermoelectric figure of merit ZT ~1 has been achieved with a single silicon nanowire and ZT ~0.5 for a porous nanowire array. Very high Seebeck coefficients (3.2 mVK−1) have been achieved in compressed nanoparticles. Data is also presented relevant to two key factors limiting performance in bulk powders. The original size of silicon particles has a significant effect on the thermal conductivities of densified pellets. The intrinsic low electric conductivity can be improved by doping either nanocrystals or surface conductive ligands.
- Porous silicon
- Seebeck coefficient