Micro-thermoelectric modules can be used to develop unique components such as energy harvesters, active coolers, and thermal sensors in various integrated systems. However, the manufacturing of these modules still relies on costly traditional micro-fabrication processes, producing only two-dimensional (2D) thermoelectric lms. This limitation severely constrains temperature gradient formation across thermoelectric lms, and hence, the su cient amount of power required to run integrated systems is not generated. Herein, we present the direct ink writing of micro-scale three-dimensional (3D) thermoelectric architectures for fabricating high-performance micro-thermoelectric generators. The characteristics of (Bi, Sb) 2 (Te, Se) 3 -based particles were precisely engineered such that the colloidal inks achieved outstanding viscoelasticity, thereby facilitating the creation of complex 3D architectures having high thermoelectric gure-of-merits of 1.1 (p-type) and 0.5 (n-type). Micro-thermoelectric generators made of 3D-written vertical laments exhibited large temperature gradients and a good resulting power density, opening an avenue for the cost-effective and rapid manufacturing of integrated micro-thermoelectric modules. Main TextMicro-thermoelectric (μ-TE) modules have been regarded as potential electronic components that can generate power from minimal heat ow or act as coolers for local heat management 1,2 . Depending on the dimensions of the TE legs, μ-TE modules can be easily integrated into various emerging systems such as Internet of things-based devices, wearable electronic devices, wireless sensor networks, and lab-on-achip devices [3][4][5] . Most of these systems are expected to be energy autonomous because they are usually embedded in enclosed environments or packaged within inaccessible structures [5][6][7] . In this context, μ-TE modules can provide a unique solution for ensuring sustainable electricity supply owing to their advantages of a simple device structure, high reliability and durability, and maintenance-free operation.Moreover, μ-TE device arrays can potentially be used in applications involving high-resolution infrared image sensors, gas sensors, and thermal imaging sensors 8 .Advancements in micro-electromechanical system (MEMS) technology have facilitated the design and fabrication of micro-scale integrated systems consisting of multiple functional units of electrical and mechanical components 9 . This micro-fabrication process based on traditional lithography, deposition, etching, and release also allows us to create patterned, planar two-dimensional (2D) TE legs and electrodes in a μ-TE module with a thickness of tens of micrometres 10,11 . However, the mass fabrication techniques used in MEMS technology have the potential problem of costly multi-step complicated processes, which rely on expensive lithography equipment. More importantly, these 2D design processes are not suitable for the fabrication of structural three-dimensional (3D) TE legs with high aspect ratios in a μ-TE module; this 3...

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Thermoelectric power generation offers a promising way to recover waste heat. The geometrical design of thermoelectric legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular thermoelectric architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu2Se thermoelectric materials. We design the optimum aspect ratio of a cuboid thermoelectric leg to maximize the power output and extend this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based thermoelectric legs. Moreover, we develop organic binder-free Cu2Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se82− polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrate the superior power output and mechanical stiffness of the proposed cellular thermoelectric architectures to other designs, unveiling the importance of topological designs of thermoelectric legs toward higher power and longer durability.

Thermoelectric (TE) technologies offer promising means to enhance fossil energy efficiencies by generating electricity from waste heat from industrial or automobile exhaust gases. For these applications, thermoelectric modules should be designed from the perspective of system integration for efficient heat transfer, system simplification, and low processing cost. However, typical thermoelectric modules manufactured by traditional processes do not fulfil such requirements, especially for exhaust pipes. Hence, a 3D‐printing method for PbTe thermoelectric materials is reported to design high‐performance power‐generating TE tubes. The electronic doping‐induced surface charges in PbTe particles are shown to significantly improve the viscoelasticities of inks without additives, thereby enabling precise shape and dimension engineering of 3D bulk PbTe with figures of merit of 1.4 for p‐type and 1.2 for n‐type materials. The performance of the power‐generating TE tube fabricated from 3D‐printed PbTe tubes is demonstrated experimentally and computationally as an effective strategy to design system‐adaptive high‐performance thermoelectric generators.

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