While zone-melted (ZM) Bi₂Te₃ is a standard commercially available thermoelectric (TE) material, it suffers from not being sufficiently mechanically robust due to the presence of the van der Waals bonded Te–Te layers that reduce the product yield and compromise operational reliability. Polycrystalline materials prepared by powder metallurgy techniques exhibit improved mechanical properties but usually lose the desired texture exhibited by ZM ingots, and this affects their TE performance. It is highly desirable to be able to fabricate Bi₂Te₃-based bulk materials with anisotropies similar to a single crystal, yet being mechanically strong as the polycrystalline specimens. Herein, we combine for the first time the thermal explosion technique with selective laser melting (SLM) to synthesize the highly textured p-type Bi_0.4Sb_1.6Te₃ bulk material. Structural analysis (FESEM and XRD) indicates that the slender columnar grains grew along the building direction (BD) of the structure and the orientation factor reached up to 0.9, close to that representing a single crystal. TEM images revealed a high density of dislocations inside the grains. Since the printed compound has a high degree of texture, the TE and mechanical properties exhibit a highly anisotropic behavior. The maximum ZT of annealed samples parallel to the BD was 1.1, similar to that of the single crystal. However, the compressive strength of the structure reached up to 91 MPa, some 2.5 times the strength of a typical single crystal (37 MPa), and even higher than that of Spark Plasma Sintered (SPS) polycrystalline samples (80 MPa). Meanwhile, the mechanical cutting performance was much superior compared to that of the ZM ingot, and TE legs could be cut to sizes as small as 0.2 mm. A micro-TE module assembled using SLM-printed high performance p-type BiSbTe and SPS-compacted n-type BiTeSe materials showed the maximum cooling temperature difference of 62 °C. The work provides a facile and effective solution for preparation of Bi₂Te₃-based materials with high texture, robust mechanical properties, and excellent TE performance. As such, it lays a solid foundation for rapid in situ 3D printing of Bi₂Te₃-based micro-TE devices.

N-type Bi₂Te_2.7Se_0.3 material fabricated by non-equilibrium laser 3D printing exhibits comparable thermoelectric properties to that of the commercially available material.

The development of wearable thermoelectric generators (w-TEGs) toward lightweight, economical and high-power-generation performance can provide more opportunities for their application in self-powered wearable electronics. For existing w-TEGs, insight into the physical parameter coupling between the substrate and TE legs is lacking, which leads to inefficient utilization of the temperature difference and deterioration of the power generation performance. In this work, comprehensive thermal management of the heat collector, TE legs and heat radiator is carried out using finite element simulation. It is found that increasing the thermal conductivity of the substrates for heat collection and dissipation is conducive to reducing the optimal fill factor and substrate thickness and improving the power density, thus facilitating comfortable-to-wear, economical, and functional w-TEGs. Specifically, a laminated film with good flexibility prepared from polyimide (PI) film and graphene assembly film (GAF) acts as the substrate of w-TEG. The PI film compensates and enhances the mechanical strength of the laminated substrate. The GAF has high thermal conductivity, which reduces the in-plane and out-of-plane thermal resistance of the laminated substrate, thus contributing to the heat collection of the bottom substrate. The GAF also has high emissivity, which enhances the radiative heat transfer and facilitates the heat dissipation of the top substrate, which is cut into blocks without affecting the electrical path to ensure the overall flexibility of the w-TEG. When the w-TEG with the laminated substrate and a fill factor of 10% (four w-TEG units connected in series, 20 × 145 mm² in plane) is worn on the wrist for running (contact pressure: 0 kPa, wind speed: 3 m s⁻¹), the optimal output voltage and power density reach 281.6 mV and 45.6 μW cm⁻², respectively, which is one of the best results among recently reported heatsink-less w-TEGs. This work provides guidance for optimizing the output performance of w-TEG and accelerating the development of self-powered electronics.