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Flexible thermoelectrics (TEs) that fit curved human skin well, could harvest energy from skin, and thus have been considered as a promising portable power source for wearable electronics. Bi2Te3, the most popular room‐temperature TE material, is still challenging to be applied in flexible devices due to its rigid nature. Although many Bi2Te3‐based films have been reported to be flexible when made thin enough, the thermal and electrical loads across them are rather small with severe limitation on the maximum power output. This work realizes a thick Bi2Te3‐based TE film with a “graphene/Bi2Te3/graphene” sandwiched structure, which demonstrates an unprecedentedly high figure of merit for flexibility among all Bi2Te3‐based films ever reported, due to the outstanding intrinsic flexibility of graphene and a small slippage barrier. Meanwhile, graphene acts as express conducting channels as well as carrier donors, resulting in an increased electrical conductivity. The numerous graphene/Bi2Te3 heterointerfaces induce energy filtering effect, leading to an enhanced Seebeck coefficient, and thus an optimized power factor is achieved. This work offers a cost‐effective avenue to make highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into 2‐dimensional nanosheets.

The past decades have witnessed surging demand for wearable electronics, for which thermoelectrics (TEs) are considered a promising self-charging technology, as they are capable of converting skin heat into electricity directly. Bi2Te3 is the most-used TE material at room temperature, due to a high zT of ~1. However, it is different to integrate Bi2Te3 for wearable TEs owing to its intrinsic rigidity. Bi2Te3 could be flexible when made thin enough, but this implies a small electrical and thermal load, thus severely restricting the power output. Herein, we developed a Bi2Te3/nickel foam (NiFoam) composite film through solvothermal deposition of Bi2Te3 nanoplates into porous NiFoam. Due to the mesh structure and ductility of Ni Foam, the film, with a thickness of 160 μm, exhibited a high figure of merit for flexibility, 0.016, connoting higher output. Moreover, the film also revealed a high tensile strength of 12.7 ± 0.04 MPa and a maximum elongation rate of 28.8%. In addition, due to the film’s high electrical conductivity and enhanced Seebeck coefficient, an outstanding power factor of 850 μW m−1 K−2 was achieved, which is among the highest ever reported. A module fabricated with five such n-type legs integrated electrically in series and thermally in parallel showed an output power of 22.8 nW at a temperature gap of 30 K. This work offered a cost-effective avenue for making highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into porous and meshed-structure materials.

Thermoelectric (TE) technology enables direct conversion between thermal and electrical energies and thus has been regarded as an alternative for energy harvesting and refrigeration. Bismuth telluride (Bi 2 Te 3 ) is the most widely used TE material at room temperature due to its high figure of merit (∼1). Since the first publication on the electrodeposition of Bi 2 Te 3 films in 1994, a large number of publications has emerged in the last two decades, owing to its advantages such as simple and safe preparation, high deposition rate, convenient micromachining, good compatibility to semiconductor microfabrication techniques and so on. This article reviews the recent research progress in the electrodeposition of Bi 2 Te 3 and its application in TE devices. Additionally, an outlook towards the future development of this area has also been discussed.

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