High thermoelectric efficiency realized in SnSe crystals via structural modulation

Abstract

Crystalline thermoelectrics have been developed to be potential candidates for power generation and electronic cooling, among which SnSe crystals are becoming the most representative. Herein, we realize high-performance SnSe crystals with promising efficiency through a structural modulation strategy. By alloying strontium at Sn sites, we modify the crystal structure and facilitate the multiband synglisis in p-type SnSe, favoring the optimization of interactive parameters μ and m*. Resultantly, we obtain a significantly enhanced PF ~85 μW cm−1 K−2, with an ultrahigh ZT ~1.4 at 300 K and ZTave ~2.0 among 300–673 K. Moreover, the excellent properties lead to single-leg device efficiency of ~8.9% under a temperature difference ΔT ~300 K, showing superiority among the current low- to mid-temperature thermoelectrics, with an enhanced cooling ΔTmax of ~50.4 K in the 7-pair thermoelectric device. Our study further advances p-type SnSe crystals for practical waste heat recovery and electronic cooling.

Lattice plainification advances highly effective SnSe crystalline thermoelectrics

“…To ensure the application of thermoelectric cooling devices, we have greatly reduced the defects concentration and improved the carrier mobility by preparing SnSe crystals ( 18 ) and modifying the crystal structure ( 23 ). By manipulating the extrinsic defects ( 24 ), using multiband synglisis strategy ( 21 ) and structural modulation ( 25 ), we further improved the room-temperature thermoelectric performance, but it is still insufficient to be practically used. For SnSe crystalline thermoelectrics, the vast off-stoichiometric defects were revealed in both undoped and doped SnSe crystals, mainly including Sn vacancies ( 24 , 26 , 27 ).…”

High Thermoelectric Performance in Cu-Doped Bi2Te2.7Se0.33 Due to Cl Doping and Multiscale AgBiSe2

“…The negative value signs show electrons as the dominant charge carriers in our samples. Additionally, the commonly observed Seebeck coefficient characteristic curve is observed as the temperature increases. − For example, at a low temperature of 300 K, the Seebeck coefficient of x = 0.65 wt % ABS is measured to be −167 μV K –1 . Subsequently, as the temperature increases to 353 K, the Seebeck coefficient decreases to −183.89 μV K –1 (indicating degenerate semiconductor behavior).…”

“…Thermoelectric materials, such as Bi 2 Te 3 -based compounds, have gained attention for converting waste heat into useful electrical energy and vice versa. − Despite their high thermoelectric performance and stability at room temperature, the practical applications of Bi 2 Te 3 -based compounds are limited due to their (n-type) relatively low thermoelectric figure of merit ( ZT ). − ZT is expressed as ZT = S 2 σ T /κ, where S , σ, T , and κ stand for the Seebeck coefficient, electrical conductivity, temperature during operation, and total thermal conductivity, respectively. In order to make these materials more practical, it is imperative to enhance certain parameters, such as the power factor (PF = S 2 σ), which should be increased, and reduce κ (κ = κ e + κ lat ), which comprises the electronic and lattice thermal conductivities .…”

Modulating structures to decouple thermoelectric transport leads to high performance in polycrystalline SnSe

“…Benefiting from the strong anharmonicity due to the layered crystal structure and the ultra-high electrical transport properties in the in-plane direction, the research on the thermoelectric properties and internal transport mechanisms of SnSe materials has rapidly become a hot issue in the thermoelectric field. 20,22–35 Resultantly, the thermoelectric properties of both p-type 36–42 and n-type 43–47 SnSe crystals have been substantially improved through years of continuous efforts by researchers. However, compared to the impressive thermoelectric properties of SnSe crystals, the thermoelectric properties of polycrystalline SnSe are not satisfactory.…”