Achieving ZT=2.2 with Bi-doped n-type SnSe single crystals

Abstract

Recently SnSe, a layered chalcogenide material, has attracted a great deal of attention for its excellent p-type thermoelectric property showing a remarkable ZT value of 2.6 at 923 K. For thermoelectric device applications, it is necessary to have n-type materials with comparable ZT value. Here, we report that n-type SnSe single crystals were successfully synthesized by substituting Bi at Sn sites. In addition, it was found that the carrier concentration increases with Bi content, which has a great influence on the thermoelectric properties of n-type SnSe single crystals. Indeed, we achieved the maximum ZT value of 2.2 along b axis at 733 K in the most highly doped n-type SnSe with a carrier density of −2.1 × 1019 cm−3 at 773 K.

Realizing High‐Ranged Out‐of‐Plane ZTs in N‐Type SnSe Crystals through Promoting Continuous Phase Transition

“…Also, significant enhancements are observed in the whole temperature range, leading to the promotion of the calculated efficiency. Compared with other reported n-type SnSe crystals, [17,21] SnSe-xPbSe crystals also reveal the overall enhancement (Figure 8c). Compared with other reported n-type SnSe crystals, [17,21] SnSe-xPbSe crystals also reveal the overall enhancement (Figure 8c).…”

Promising Thermoelectric Bulk Materials with 2D Structures

“…The special structure also leads to ultralow thermal conductivities of 0.7 and 0.34 W m −1 K −1 for the SnSe crystal at room temperature and 773 K along the b axis and a axis, respectively. Combining the advantages of the relatively high power factor and low thermal conductivity, the ZT value, shown in Figure 3d, of the SnSe crystal reaches a high level, approaching 2.3 at 773 K for p type SnSe [11] and 2.2 at 723 K for n type SnSe [20] along the bc plane.…”

“…[80] According to solid state physical principles, the ZT value for bulk mate rials with a single parabolic band (SPB) along a certain direc tion can be given as: [4] The timeline for thermoelectric bulk materials with 2D structures, showing data from a superlattice, [8] SnSe, [11,[19][20][21] Bi 2 Te 3 , [12,14,16,17,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] BiCuSeO, [12,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] Na x CoO 2 , [57,58] Ca 3 Co 4 O 9 , [5...…”

Heavy Doping by Bromine to Improve the Thermoelectric Properties of n‐type Polycrystalline SnSe

“…However, since intrinsic Sn vacancy shows p‐type conducting behavior, it is difficult to convert SnSe to n‐type conductor, much more difficult to activate the heavy conduction band22 if compared with p‐type SnSe. I,23 BiCl 3 ,24 Bi,25 and Br26 have been proved capable of changing the Hall coefficient from positive to negative. A decent ZT of ≈0.8 at about 773 K was obtained in SnSe 0.96 I 0.04 with room temperature electron carrier concentration ≈2.0 × 10 17 cm −3 23.…”