Large-area, Solution Process Two-Dimensional MoS2 Thermoelectric Generator via Electrochemical Exfoliation

In recent years, thermoelectric generators (TEGs) have received considerable attention in energy harvesting for their ability to convert temperature differences into electrical voltage without an external power supply. They are therefore considered promising for harvesting waste heat and enabling self-powered electronic systems. Among various thermoelectric materials, two-dimensional (2D) materials, known for their intrinsically high Seebeck coefficient, have emerged as strong candidates for thermoelectric applications, although their low electrical conductivity often limits the overall power factor (PF). While previous studies have attempted to address this issue through doping, such approaches can introduce charged impurities that act as scattering centers and degrade carrier mobility. Instead, we employed electrochemically exfoliated (ECE) MoS2. ECE MoS2 is known to contain a higher density of sulfur vacancies generated during the exfoliation process, which can significantly enhance electrical conductivity without additional doping. Moreover, ECE MoS2 ink, followed by a solution process, can yield scalable and uniform films for large-area processing. Using this approach, we fabricated a large-area ECE MoS2 TEG. The device exhibited a high Seebeck coefficient (S) of –215 μV·K–1, which is comparable to previously reported mechanically exfoliated MoS2 based TEGs. This demonstrates that sulfur-vacancy-induced carrier modulation in ECE MoS2 can effectively improve electrical transport without external dopants. Overall, this work provides a scalable and efficient strategy for the fabrication of large-area 2D thermoelectric devices and paves the way for the practical realization of high performance, self-powered electronic systems.