## 4 Conclusions  
Microwave assisted polyol synthesis was used to fabricate high-purity nanostructured Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) (where x: 0-2) thermoelectric materials in a matter of minutes, in a very highly reproducible manner. Besides dramatically shortening the synthesis time, the quantities that can be fabricated per batch (>8 g) is unprecedented in other solution synthetic techniques. Fabricated materials exhibit hexagonal (or truncated hexagonal) platelet particle morphology in agreement with the rhombohedral crystal structure. Thermoelectric performance of Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) pellets were studied, where the highest ZT values of 1.04 (at 440 K) for x: 0 (Bi\({}_{2}\)Te\({}_{3}\)) and 1.37 (at 523 K) for x: 2 (Sb\({}_{2}\)Te\({}_{3}\)) were obtained, respectively, as n- and p-type TE materials. Ternary compositions, where x: 0.2 and 1.5, reached ZT of 0.8-0.9 at 523 K, which are also promising values for thermoelectric conversion. The large density of grain boundaries has been effective in reducing the thermal conductivity of the materials, thus making it possible to achieve ZT values in the order of 1 or above for pure phases of Bi\({}_{2}\)Te\({}_{3}\) and Sb\({}_{2}\)Te\({}_{3}\). Furthermore, due to their small size and favorable surface chemistry, the as-made nanoparticles could easily be used to fabricate hybrid thermoelectric films. The devised MW-assisted synthesis technique, which is energy and resource effective resulting in thermoelectric materials with promising performance, opens avenues for large scale production of heat-energy harvesting materials. In addition, complete thermoelectric devices can be realized by combining our n-type and p-type Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) materials. Furthermore, the presented method is truly scalable and can be tuned for one-pot synthesis of even quaternary compositions such as (BiSb)\({}_{2}\)(TeSe)\({}_{3}\). **Supplementary Materials:** The following are available online at [[http://www.mdpi.com/2076-3417/10/3/1178/s1](http://www.mdpi.com/2076-3417/10/3/1178/s1)]([http://www.mdpi.com/2076-3417/10/3/1178/s1](http://www.mdpi.com/2076-3417/10/3/1178/s1)), Table S1. Literature review on microwave (MW)-assisted synthesis of Bi\({}_{2}\)Te\({}_{3}\). Details of the synthetic route (solvent, reactor), reaction temperature-time; morphology of resultant structures; the quantity typically obtained according to described procedure in the articles; and the reported transport data. Figure S1. (a) Screenshot of the reactor for experimental design using multivessel rotor. (b) Multivessel high pressure rotor used for the MW-assisted synthesis of Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) nanoparticles. The system can take up to 15 reactors, which can be filled up to about 100 mL each, making it possible to synthesize high and reproducible quality nanostructures with a high yield, at a pilot scale, without needing any complicated or reflux systems. Figure S2. (a) Typical temperature (T)-time (t)-power (P) profile of the MW-assisted synthesis process for Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) samples. (b) As-synthesized sample transferred to a centrifuge vial and phase separation is easily achieved, yielding typically 2-3 g sample per reactor vessel. Four positions/vials (out of 15) during the MW-assisted reaction is sufficient to prepare 8-10 g of these materials within a reaction time of 2 min. Figure S3. Reaction mechanism showing the molecular structure of organic components used for the polyol synthesis of Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) nanoparticles. While Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) nanoparticles are formed, ethylengelvool (EG) is converted to diacetyl (rxn (1)) and trioctylphosphine (TOP) is converted to trioctylphosphine oxide (TOPO) (rxn (2)). Figure S4. Estimated change of the lattice parameter a (or b) by substitution of Sb (x) in Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) system. Figure S5.