Approximately 90% of the world’s energy is produced from heat engines working near 40% efficiency. Annually, this results in the loss of 30 PWh of wasted heat for the 20 PWh of usable energy produced. Thermoelectric materials, which convert heat directly into electrical energy, present a way to utilize this wasted heat. Group IV elements are attractive as thermoelectric materials due to their nontoxicity and relative abundance. Silicon–germanium alloys have been studied for their thermoelectric properties for decades. However, the high cost of germanium and moderate efficiency has traditionally limited their usefulness. Recent studies have shown that incorporation of as little as 5% germanium into silicon has been shown to greatly improve thermoelectric properties in bulk systems. However, the successes seen in bulk alloying studies have not yet been translated to nanoscale materials. Nanoscaling of thermoelectric materials provides greater flexibility for manipulating the parameters that govern a material’s thermoelectric performance, such as band gap, electrical and thermal conductivity, and carrier concentration. Development of a colloidal synthesis of Group IV-based materials could allow for the generation of tunable thermoelectric materials in a scalable manner, from commercially available materials. Here, we present a solution-based bottom-up approach to the synthesis of alloyed silicon-germanium nanoparticles in a non-coordinating solvent and illustrate the effect of compositional tuning on the resulting products.

Synthesis of silicon-germanium alloy nanoparticles for thermoelectric applications

249th National Meeting (2015)

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