Optimizing Room-Temperature Thermoelectric Performance of n-Type Bi₂Te_2.7Se_0.3

Abstract

Bi 2 Te 3 -based compounds are exclusive commercial thermoelectric materials around room temperature. For n-type compounds, optimal thermoelectric properties are normally obtained at temperatures higher than room temperature to suppress the bipolar effect through increased carrier concentration. We find that doping with trace amounts of Cd and the addition of excess Bi are effective ways to optimize carrier concentration and achieve enhanced room-temperature thermoelectric performance for the Bi 2 Te 2.7 Se 0.3 alloy in this work. For the Cd-doped samples, the replacement of Cd with Bi leads to not only a significant decrease in electron concentration but also apparently reduces the total thermal conductivity. The addition of excess Bi in the samples creates a Bi-rich synthetic atmosphere during the synthesis process, leading to increased Bi Te antisite defects, decreased electron concentration, and reduced total thermal conductivity. Doping a small amount of Cd or adding excess Bi causes optimal thermoelectric performance of the n-type Bi 2 Te 2.7 Se 0.3 sample shifts obviously toward low temperatures, and the samples with 0.4 atom % Cd and 0.8 atom % excess Bi achieve maximum zT of ∼0.97 at 448 K and ∼0.88 at 348 K, respectively.

Fine-Grained Bi–Sb Ribbons with Modulation-Doped FeSb Nanoparticles for High-Temperature Cryogenic Applications

“…38,49 Under a similar assumption, the SPB model has also been applied to analyze several complex (including modulated) alloys. 18,38,49,50 It is worth noting that the carrier concentration in Bi 1−x Sb x alloy in the present case does not change much in going from x = 0.13 to 0.26, and the calculated n H values are comparable. This indicated that the carrier concentration for intermediate values of x (0.13 ≤ x ≤ 0.26) in the Bi 1−x Sb x alloy remained practically independent of the Sb content.…”

“…Assuming the single parabolic band (SPB) conduction model, we calculated the Hall carrier concentration n H (shown in Figures S4a) using n H = 1/ eR H , where e is the electronic charge. The single parabolic band (SPB) conduction model seems to be a good approximation for the analysis of modulated samples prepared in this study, which is based on the assumption that acoustic phonon and alloying scattering dominate carrier transport. , Under a similar assumption, the SPB model has also been applied to analyze several complex (including modulated) alloys. ,,, It is worth noting that the carrier concentration in Bi 1– x Sb x alloy in the present case does not change much in going from x = 0.13 to 0.26, and the calculated n H values are comparable. This indicated that the carrier concentration for intermediate values of x (0.13 ≤ x ≤ 0.26) in the Bi 1– x Sb x alloy remained practically independent of the Sb content.…”

“…The few state-of-the-art TE materials with a decent ZT at low and room temperatures that have been identified include Bi 1– x Sb x , , Bi 2 Te 3 , , CsBi 4 Te 6 , , Mg 3 Bi 2– x Sb x , YbAgCu 4 , etc. It is important to note that only Bi 1– x Sb x is able to perform in the mid-cryogenic temperature range ( T < 150 K) .…”

Enhancing the thermoelectric performance of n-type Bi2Te2.7Se0.3 through the incorporation of Ag9AlSe6 inclusions

“…S6 (ESI) †. Clearly, the obtained large ZT values of the present BTS-based composites incorporating Ag 9 AlSe 6 inclusions are larger than most of the reported ZT values in typical n-type BTS-based composite systems 21,23,30,34–38 (see Fig. 5).…”

“…An enhancement of the ZT ave value can be found for the samples of BTS-0. larger than most of the reported ZT values in typical n-type BTS-based composite systems 21,23,30,[34][35][36][37][38] (see Fig. 5).…”