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Bi2Te3-based materials are promising candidates for near-room-temperature applications due to their high thermoelectric performance and low cost. Here, an innovative thermal diffusion strategy combined with magnetron sputtering and thermal evaporation methods was employed to fabricate Bi2Te3 flexible thin films (f-TFs) on a flexible polyimide substrate. An in situ synthesis of Bi2Te3 f-TFs with good crystallinity was obtained using a straightforward thermal diffusion method through diffusion of Te into a Bi precursor under low vacuum conditions (1 × 105 Pa). This method offers easy preparation, low cost, and a large-area film preparation for industrialization. The electrical conductivity increases with increasing thermal diffusion temperatures. A high room temperature carrier mobility of ~28.7 cm−2 V−1 S−1 and an electrical conductivity of ~995.6 S cm−1 can be achieved. Then, a moderate room temperature Seebeck coefficient >100 μV K−1 was obtained due to the chemical stoichiometry being close to the standard by optimizing the thermal diffusion temperature. Consequently, a maximum room temperature PF of ~11.6 μW cm−1 K−1 was observed in Bi2Te3 f-TFs prepared using a thermal diffusion temperature of 653 K. The thermal diffusion strategy applied in the thin film preparation represents an effective approach for the preparation of high thermoelectric performance Bi2Te3 f-TFs, offering a promising route for future thermoelectric applications. [ABSTRACT FROM AUTHOR]

Flexible Sb2Te3-based thermoelectric (TE) materials are promising candidates for fabricating energy devices that power wearable electronics and sensors. Enhancing the TE properties of Sb2Te3 thin films represents a significant scientific investigation. In this work, a thermal diffusion method is applied to prepare the In-doped Sb2Te3 thin film. In doping can lead to a high Seebeck coefficient of ~137.04 μV K−1 as well as moderate electrical conductivity. As a result, the high power factor of ~18.22 μW cm−1 K−2 at 303 K is achieved. Moreover, In doping could reduce the thermal conductivity owing to the increase in phonon scattering. Finally, the high ZT values of ~0.47 at room temperature (303 K) and ~0.6 at 453 K are obtained. This indicates that In doping is a highly promising and effective approach to improving the TE performance of Sb2Te3 thin films. [ABSTRACT FROM AUTHOR]

Inorganic n-type Bi2Te3 flexible thin film, as a promising near-room temperature thermoelectric material, has attracted extensive research interest and application potentials. In this work, to further improve the thermoelectric performance of flexible Bi2Te3 thin films, a post-electric current treatment is employed. It is found that increasing the electric current leads to increased carrier concentration and electric conductivity from 1874 S cm−1 to 2240 S cm−1. Consequently, a high power factor of ~10.70 μW cm−1 K−2 at room temperature can be achieved in the Bi2Te3 flexible thin films treated by the electric current of 0.5 A, which is competitive among flexible n-type Bi2Te3 thin films. Besides, the small change of relative resistance <10% before and after bending test demonstrates excellent bending resistance of as-prepared flexible Bi2Te3 films. A flexible device composed of 4 n-type legs generates an open circuit voltage of ~7.96 mV and an output power of 24.78 nW at a temperature difference of ~35 K. Our study indicates that post-electric current treatment is an effective method in boosting the electrical performance of flexible Bi2Te3 thin films. [ABSTRACT FROM AUTHOR]

Nanocomposite engineering decouples the transport of phonons and electrons. This usually involves the in-situ formation or ex-situ addition of nanoparticles to a material matrix with hetero-composition and hetero-structure (heC-heS) interfaces or hetero-composition and homo-structure (heC-hoS) interfaces. Herein, a quasi homo-composition and hetero-structure (hoC-heS) nanocomposite consisting of Pnma Bi2SeS2 - Pnnm Bi2SeS2 is obtained through a Br dopant-induced phase transition, providing a coherent interface between the Pnma matrix and Pnnm second phase due to the slight structural difference between the two phases. This hoC-heS nanocomposite demonstrates a significant reduction in lattice thermal conductivity (~0.40 W m−1 K−1) and an enhanced power factor (7.39 μW cm−1 K−2). Consequently, a record high figure-of-merit ZTmax = 1.12 (at 773 K) and a high average figure-of-merit ZTave = 0.72 (in the range of 323–773 K) are achieved. This work provides a general strategy for synergistically tuning electrical and thermal transport properties by designing hoC-heS nanocomposites through a dopant-induced phase transition. Most of the thermoelectric nanocomposites have structure character of a hetero-composition and hetero-structure, or hetero-composition and homo-structure between matrix phase and dispersion phase. This work shows a quasi homo-composition and hetero-structure (hoC-heS) nanocomposite consisting of Pnma Bi2SeS2 - Pnnm Bi2SeS2 with high ZT. [ABSTRACT FROM AUTHOR]