Use of electrochemical etching to produce doped phenylacetylene functionalized particles and their thermal stability

Silicon is an attractive material for the fabrication of thermoelectric materials. Previously, it was reported that phenylacetylene capped silicon nanoparticles (PA-SiNPs), which were synthesized from micelle reduction, displayed a ZT of up to 0.6 at ambient temperature. The major contributing factor to this result was the material’s low thermal conductivity. However, this material also displayed a low electrical conductivity compared to other thermoelectric materials. This is contributed to, in part, by low charge carrier concentration, which is difficult to control in micelle reduction-based methods. Top–down methods allow control of the carrier concentration as the material is doped prior to the breaking down of the material. PA-SiNPs were synthesized using electrochemical etching followed by functionalization. These particles were then analyzed with transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The DSC and TGA trace were compared to those of PA-SiNPs synthesized by micelle reduction to show that the thermal stability range is much higher in the particles synthesized from the top–down method giving them a wider range of potential thermoelectric applications.