Enhanced mid-temperature thermoelectric performance of textured SnSe polycrystals made of solvothermally synthesized powders

Abstract

A highZTof up to 0.6 at 773 K with improved mid-temperature thermoelectric performance is achieved for textured SnSe polycrystals without deliberate doping.

Texturing degree boosts thermoelectric performance of silver-doped polycrystalline SnSe

“…The highest reported ZT for polycrystalline SnSe is only 1.1, which is less than half of the undoped SC. 15,16 Even though alloying and microstructure modulation have been used to reduce thermal conductivity, polycrystalline samples exhibit a higher κ than the SC, [15][16][17][18][19][20] which contradicts phonon scattering considering the effect of grain boundary scattering. In addition, most polycrystalline samples possess lower power factors (S 2 σ) than the SC, which suggests that the control of crystallite orientation is very important in polycrystalline SnSe samples.…”

“…In addition, most polycrystalline samples possess lower power factors (S 2 σ) than the SC, which suggests that the control of crystallite orientation is very important in polycrystalline SnSe samples. [15][16][17][18][19][20] The undoped SnSe shows a carrier concentration of~10 17 cm − 3 , 11 which is considerably lower than the optimal region for a thermoelectric material. [2][3][4] Therefore, chemical doping has been used to tune the carrier concentration and improve the thermoelectric performance of SnSe.…”

“…12,13 However, the doped polycrystalline samples still show ZT values that are less than 1.1, which is the highest reported value of undoped polycrystalline samples, although the carrier concentration has been optimized to 410 19 cm − 3 . [19][20][21][22][23][24][25][26][27][28][29][30] The deep understanding of electrical and thermal transport properties and exquisite control of the crystallite orientation in the samples are essential to achieve high thermoelectric performance in polycrystalline SnSe.…”

Thin Film Tin Selenide (SnSe) Thermoelectric Generators Exhibiting Ultralow Thermal Conductivity

“…[16][17][18][19][20][21][22][23][24] Sassi et al synthesized polycrystalline SnSe in quartz tubes and then densified by spark plasma sintering (SPS) and showed a peak ZT value of 0.5 at 823 K. [16] Li et al achieved a ZT of 0.58 at 773 K in textured SnSe polycrystals fabricated by the solvothermal synthesis (SS) followed by SPS. [21] Shi et al used the same technique but self-doped (SD) with Se to achieve a higher ZT of 1.36 ± 0.12 at 823 K. [17] Wei et al achieved a ZT of 0.8 at 800 K in polycrystalline SnSe with Na doping by using a combination of melting (M) and SPS. [18] Li et al achieved a ZT of 0.54 at 790 K by melting annealing (MA) and SPS.…”

“…This compares to observed peak positions of 485.6-485.9 eV for Sn 3d 5/2 and 53.6-53.7 eV for Se 3d 5/2 peaks observed elsewhere for stoichiometric SnSe systems. [21,26,36] This slight discrepancy in peak position for Se is attributed to the unusual stoichiometry of the present system, with the Se remaining relatively electron dense compared to the Se(0) value of 55.2 eV. [38] In both the cases, the sharp peaks with full width half maximum (FWHM) < 1 eV indicate a single bonding environment with no evidence of a SnO 2 peak at 486.7 eV or a Se 4+ peak in the region of 58-59 eV.…”