Atomic Interface Engineering in Two-Dimensional Materials: A Pathway to High-Performance Flexible Thermoelectrics

Thermoelectric (TE) energy conversion, which directly transforms waste heat into usable electricity, presents a crucial technology for sustainable power generation and energy efficiency enhancement. The emergence of two-dimensional (2D) materials has profoundly impacted this field by providing an atomically thin platform for unprecedented control over electronic and thermal transport properties. This comprehensive review critically analyzes the latest progress, persistent challenges, and future opportunities of 2D materials for advanced TE applications. We begin by systematically evaluating the synthesis and processing toolkit, correlating techniques from top-down exfoliation to bottom-up chemical vapor deposition with their specific impacts on microstructure and final device performance. Subsequently, we provide a critical assessment of the fundamental TE performance of key 2D families, including graphene, transition metal dichalcogenides (TMDs), MXenes, black phosphorus (BP), and hexagonal boron nitride (h-BN). The discussion details how advanced engineering strategies, such as strain modulation, layer number control, chemical doping, and heterostructure (HS) design, can dramatically enhance the power factor (PF) while simultaneously suppressing lattice thermal conductivity (κ_L). Finally, we showcase the successful translation of these materials into practical applications, encompassing flexible and wearable TE generators (WTEGs), self-powered sensors, and integrated energy harvesting systems.