Carbon- and boron-based nano-inclusions for thermoelectric nanocomposites: Matrix matching and interface design.

Nanocomposite engineering offers a route to improve thermoelectric (TE) performance by modifying the coupled transport of charge carriers and phonons. This review examines carbon- and boron-based nanoinclusions across bismuth chalcogenides, Cu2Se, oxide matrices, and flexible polymer- and film-based thermoelectrics, with emphasis on inclusion chemistry, dimensionality, loading, processing route, and interface engineering. Bismuth chalcogenides generally require a narrow loading window because additional interfaces can degrade carrier mobility, whereas Cu2Se more readily accommodates such interfaces and has high zT values > 2. In oxides, improved electrical transport is often insufficient to offset high lattice thermal conductivity, while flexible systems require consideration of power factor, mechanical durability, and device output. Cross-system comparison shows that effective nanoinclusion design depends on balancing phonon suppression with carrier transport and interfacial stability, providing practical guidance for thermoelectric materials and device development.