In recent decades, thermoelectric (TE) materials have proven to be a complementary source of renewable energy, as they can directly convert waste heat into electrical energy. Energy-efficient, reliable, and scalable synthetic routes for the fabrication of TE materials and their processing into functional devices via low-energy and low-waste routes are necessary for the broader adoption of these materials in various applications. In this work, we report the formulation of hybrid thermoelectric ( h TE) inks based on nanostructured Sb₂Te₃ and Bi₂Te₃, using PMMA as the polymer matrix and hexanedithiol (HDT) as the binder. Percolation studies were conducted to determine the optimal film composition, with an 80% nanoparticle content yielding the highest TE performance. Finite element modelling (FEM) was employed to optimize the device geometry, including the cross-sectional area ratio of p- and n-type legs, to maximize power output. Based on these results, a flexible h TEG was fabricated using the optimized ink composition. The device exhibited an output power of 950 nW and a Power output Density (PoD) of 40.37 nW cm⁻² under a 30 K temperature gradient, significantly outperforming previously reported polymer-based flexible h TEGs incorporating chalcogenides. This study presents a sustainable and effective strategy for developing high-performance hybrid thermoelectric devices through ink formulation, composition optimization, and simulation-guided device design.

Thermoelectric (TE) materials can directly convert heat into electrical energy. However, they sustain costly production procedures and batch-to-batch performance variations. Therefore, developing scalable synthetic techniques for large-scale and reproducible quality TE materials is critical for advancing TE technology. This study developed a facile, high throughput, solution-chemical synthetic technique. Microwave-assisted thermolysis process, providing energy-efficient volumetric heating, was used for the synthesis of bismuth and antimony telluride (Bi2Te3, Sb2Te3). As-made materials were characterized using various techniques, including XRPD, SEM, TEM, XAS, and XPS. Detailed investigation of the local atomic structure of the synthesized Bi2Te3 and Sb2Te3 powder samples was conducted through synchrotron radiation XAS experiments. Radial distribution functions around the absorbing atoms were reconstructed using reverse Monte Carlo simulations, and effective force constants for the nearest and distant coordination shells were subsequently determined. The observed differences in the effective force constants support high anisotropy of the thermal conductivity in Bi2Te3 and Sb2Te3 in the directions along and across the quintuple layers in their crystallographic structure. The as-made materials were consolidated via Spark Plasma Sintering to evaluate thermal and electrical transport properties. The sintered TE materials exhibited low thermal conductivity, achieving the highest TE figure-of-merit values of 0.7 (573 K) and 0.9 (523 K) for n-type Bi2Te3 and p-type Sb2Te3, respectively, shifted significantly to the high-temperature region when compared to earlier reports, highlighting their potential for power generation applications. The scalable, energy- and time-efficient synthetic method developed, along with the demonstration of its potential for TE materials, opens the door for a wider application of these materials with minimal environmental impact.

With the recent advances in thermoelectric (TE) technology, there is an increasing demand to develop thick films that would enable large-scale TE devices. Assembly of TE-films from size and morphology-controlled nano particles has been a challenging issue that can be addressed by the use of electrophoretic deposition (EPD) technique. In this work, morphology-controlled Sb2Te3 nanoparticles were synthesized through microwave assisted thermolysis, which were subsequently used for EPD of TE films on specially developed glass substrates. The electronic transport properties were measured in the temp-range of 22-45 degrees C. The as-made EPD films showed a high initial resistance, ascribed to high porosity and the presence of surface oxide/passivating layers. The impact of two types of small organic molecules-as hexanedithiol and dodecanethiol, on the electronic transport was investigated, resulting in a significant improvement in the electrical conductivity of the films. The XPS analysis suggests that the thiols bind to the surface of nanoparticles through formation of sulfides. Seebeck coefficient in the range of + 160 to + 190 & mu;V/K was measured, revealing the p-type transport through the deposited films. Finally, a power factor of about 2.5 & mu;W/K2.m was estimated the first time for p-type EPD films, revealing the potential of the developed nanoparticles and substrate, the small molecule additives and the EPD process presented in this work.