BiSb 2Te3 Research Articles

Exceptional thermoelectric and mechanical performance in (Bi, Sb)2Te3 matrix facilitated by AgInSe2 alloying

The emerging fields of the Internet of Things, intelligent robotics, and smart biomedical devices have sparked an increasing demand for high-performance thermoelectric (TE) devices due to their efficient conversion of thermal energy into electrical power, and vice versa. The environmentally friendly (Bi, Sb)2Te3 (BST) system, which displays superior performance near room temperature, offers a promising solution for optimizing thermoelectrics to meet the needs of commercial applications. Here, we utilized AgInSe2 alloying to enhance the TE and mechanical properties of BST, aiming to optimize electron and phonon transport and elucidate the underlying mechanisms. The synergistic optimization resulted in a peak zT of ∼ 1.3 at 353 K and an average zTave of ∼ 1.11 from 303 K to 503 K in BST-0.1 %AgInSe2, as well as a high Vickers hardness of ∼ 105 Hv. Through rational optimization of the TE device, we achieved a maximum conversion efficiency of ∼ 6 % at a temperature difference of 210 K. Leveraging the robust TE output of the device, we further evaluated its potential as a self-powered information interaction wristband device based on ASCII codes. We envisage this versatile TE device being extensively applied in power generation and human–machine interaction, with promising potential in wearable electronics, telecommunications, and healthcare monitoring.

Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering

Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)2Te3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (λIEE) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that λIEE is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin–orbit coupling between the BST and the CoFeB. Our work provides a method to enhance λIEE and is useful for the understanding of charge-to-spin conversion in TI-based systems.

High‐Efficiency Thermoelectric Power Generation Enabled by Homogeneous Incorporation of MXene in (Bi,Sb)2Te3 Matrix

AbstractThe (Bi,Sb)2Te3 (BST) compounds have long been considered as the benchmark of thermoelectric (TE) materials near room temperature especially for refrigeration. However, their unsatisfactory TE performances in wide‐temperature range severely restrict the large‐scale applications for power generation. Here, using a self‐assembly protocol to deliver a homogeneous dispersion of 2D inclusion in matrix, the first evidence is shown that incorporation of MXene (Ti3C2Tx) into BST can simultaneously achieve the improved power factor and greatly reduced thermal conductivity. The oxygen‐terminated Ti3C2Tx with proper work function leads to highly increased electrical conductivity via hole injection and retained Seebeck coefficient due to the energy barrier scattering. Meanwhile, the alignment of Ti3C2Tx with the layered structure significantly suppresses the phonon transport, resulting in higher interfacial thermal resistance. Accordingly, a peak ZT of up to 1.3 and an average ZT value of 1.23 from 300 to 475 K are realized for the 1 vol% Ti3C2Tx/BST composite. Combined with the high‐performance composite and rational device design, a record‐high thermoelectric conversion efficiency of up to 7.8% is obtained under a temperature gradient of 237 K. These findings provide a robust and scalable protocol to incorporate MXene as a versatile 2D inclusion for improving the overall performance of TE materials toward high energy‐conversion efficiency.

Fabrication of Silver-Doped (Bi,Sb)₂Te₃ Thermoelectric Film Prepared from Ag Nanoparticles/Bi-Sb-Te Pastes.

Film-type thermoelectric generator (TEG) utilizing Bi-Te based paste has been highly considered as advanced power sources for the wearable electronic devices due to its light, thin and flexible characteristics when producing electricity from certain thermal resources such as human body heat. However, the application of the film-typed TEG has been often limited due to its low TE conversion efficiency caused by low electrical conductivity resulting from severe porosity. Thus, it is crucial to increase electrical properties via densification of the TE film. Here, we synthesized silver nanoparticle (AgNP)-dispersed (Bi,Sb)₂Te₃ (BSbT) powders to fabricate AgNP-BSbT pastes by adding organic binder. The synthesized AgNP-BSbT pastes were printed through a hand-painting process and were consolidated into Ag-doped BSbT (Ag-BSbT) thick film with a few hundreds μm with controlled 2-step heat treatment. The microstructures of Ag-BSbT films show abnormally elongated grains but also the amount of porosities in the film significantly decreased by addition of AgNP. As a result, it is confirmed that the 0.072 at% Ag-BSbT thick film exhibits power factor of 2.93 × 10-3 W/mK² at room temperature, which is comparable to that of practically utilized bulk materials. It is elucidated that the increase in power factor originates from the modulation between electrical conductivity and Seebeck coefficients due to increased hole carrier density at room temperature.

Scanning thermoelectric microscopy of local thermoelectric behaviors in (Bi,Sb)2Te3 films

In this paper we develop scanning thermoelectric microscopy (STeM) on the basis of commercial atomic force microscope. The nanoscale thermoelectric behaviors of (Bi,Sb)2Te3 (BST) thin films were studied. 3ω-technique was used for thermal conductivity imaging and quantitative thermal characterization. By acquiring the unique Seebeck information from 2ω frequency component, nanoscale thermoelectric images were firstly obtained, exhibiting remarkably inhomogeneous distribution of local Seebeck coefficient in the thin films. Positive thermoelectric response is revealed by the modulation of temperature difference between thermal tip and sample, corresponding to p-type conduction within BST sample.