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Owing to the unique features, such as mechanically robust, low-toxic, high stability, and high thermoelectric performance, CoSb3-based skutterudite materials are among art-of-the state thermoelectric candidates. In this work, we develop a facile in-situ method for the growth of well-crystallinity (Ag, Sn) co-doped CoSb3 thin films. This preparation method can efficiently control the dopant concentration and distribution in the thin films. Both the density functional theory calculation and the experimental results suggest that Sn and Ag dopants trend to enter the lattice and preferentially fill interstitial sites. Additionally, band structure calculation results suggest that the Fermi level moves into the conduction bands due to co-doping and eventually induces the increased electrical conductivity, which agrees with the optimization of carrier concentration. Moreover, an increase in the density of state after co-doping is responsible for the increased Seebeck coefficient. As a result, the power factors of (Ag, Sn) co-doped CoSb3 thin films are greatly enhanced, and the maximum power factor achieves over 0.3 mW m−1 K−2 at 623 K, which is almost two times than that of the un-doped CoSb3 film. Multiple microstructures, including Sb vacancies and Ag/Sn interstitial atoms as point defects, and a high density of lattice distortions coupled with nano-sized Ag-rich grains, lead to all scale phonon scatterings. As a result, a reduced thermal conductivity of ∼0.28 W m−1 K−1 and a maximum ZT of ∼0.52 at 623 K are obtained from (Ag, Sn) co-doped CoSb3 thin films. This study indicates our facile in-situ growth can be used to develop high-performance dual doped CoSb3 thins.

Recently, fabrication of high-efficiency miniature thermoelectric devices with thin films has attracted great attention. ZnSb-based thin films have been widely studied owing to their advantages of earth-abundant, eco-friendly, and excellent electron transport properties. However, its thermoelectric performance at room temperature is still low which extremely restricts its application. In this work, we report a high-power factor of 6.2 μWcm −1K−2 and a record-high thermoelectric figure of merit, ZT of 0.35 at room temperature from the non-stoichiometric ZnSb-based thin film, fabricated by a facile magnetron cosputtering technique. Extensive characterizations reveal that all the prepared films have a primary ZnSb phase with good crystallinity, leading to high electrical conductivity . Meanwhile, the carrier concentration is optimized with Zn addition, which contributes to a high Seebeck coefficient, resulting in a decent power factor. Simultaneously, the Zn-rich films also show nanopores , Zn-rich nanophases, and Zn 4Sb3 nano inclusions. These induced nanostructures enhance the scattering of medium- and long-wavelength phonons, contributing to the reduction of lattice thermal conductivity . This work demonstrates that rational nanostructure manipulations can achieve high performance in ZnSb thin films, which possess potential applications for the fabrication of miniature thermoelectric devices.

The sulfide compound Bi2SeS2 is an environmentally friendly thermoelectric material, which is as an analogy of the traditional compound Bi2S3. Here, a high ZT value of 1.04 at 773 K is obtained through synergistically tuning the electrical transport properties by using Cu and I as the dual carrier providers and suppressing the lattice thermal conductivity by forming the Cu-rich nano-precipitates. The dual carrier providers lead to exclusively high electrical conductivity and hence a large power factor over 650 μWm−1K−2 at 773 K. The atomic resolved annular dark field STEM reveals the interstitial Cu and S deficiency would result into the formation of BiCuS2 or Cu2S nano-precipitates and embed in the lattice of Bi2SeS2, serving as strong phonon scattering. This work suggested that nanostructured Bi2SeS2 is very promising for waste heat energy harvesting in the future.

n-type Bi2Te2.7Se0.3 (BTS) alloy is a state-of-the-art room temperature thermoelectric material used for refrigeration commercially. However, wide application is limited by its low performance. Here, we show that incorporation of nano-sized 3D topological insulator (3D-TI) Bi2Se3 in Bi2Te2.7Se0.3 bring about a large electron mobility and increased electrical conductivity owing to the enhanced contribution of topologically protected conducting surface states as well as large Seebeck coefficient due to energy dependent carrier scattering. Besides, the incorporation of 3D-TI nanoinclusions leads to enhanced phonon scattering. As a result, addition of 0.3 vol% of Bi2Se3 in BTS results in ~ 36% increase in power factor and ~ 16% decrease in total thermal conductivity, leading to a large figure of merit ZTmax = 1.28 (at 375 K) and a large average ZTave = 1.16 (at T = 300–525 K), which are 62% and 59% greater than that of BTS, respectively.

Although n-type Bi2Te3-based alloys are state-of-the-art thermoelectric material, their efficiency is still too low to satisfy its wide applications. Hence, it is imperative to improve the thermoelectric performance of n-type Bi2Te2.7Se0.3 (BTS). Here, we show that through a facile method of Sn addition in BTS a new SnxBi2Te2.7Se0.3 based nanocomposite embedded with in-situ formed SnBi and Te nanoinclusions ((SnBi + Te)/SnxBi2Te2.7Se0.3) is constructed, and its thermoelectric performance is enhanced substantially as compared to pristine BTS. Specifically, addition of 0.2 wt% of Sn in BTS causes 38% increase in power factor (PF) and 40% reduction in lattice thermal conductivity. The increased PF mainly comes from elevated Seebeck coefficient due to intensified energy dependent electron scattering caused by the interface potentials; while the reduced thermal conductivity originates from enhanced phonon scattering by the embedded nanoinclusions. Consequently, both high maximum figure of merit ZT (ZTmax = 1.11 at ~370 K) and large average ZT (ZTave = 1.03 at T = 300 K–500 K) are achieved for this sample, which are respectively 76% and 80% higher than those of BTS studied here.