Binary and Ternary Colloidal Cu‐Sn‐Te Nanocrystals for Thermoelectric Thin Films

Abstract

Recent advances in copper chalcogenide-based nanocrystals (NCs), copper sulfide, and copper selenide derived nanostructures, have drawn considerable attention. However, reports of crystal phase and shape engineering of binary or ternary copper telluride NCs remain rare. Here, a colloidal hot-injection approach for producing binary copper/tin telluride, and ternary copper tin telluride NCs with controllable compositions, crystal structures, and morphologies is reported. The crystal phase and growth behavior of these tellurides are systematically studied from both experimental and theoretical perspectives. The morphology of Cu 1.29 Te NCs is modified from 1D nanorods with different aspect ratios to 2D nanosheets and 3D nanocubes, by controlling the preferential growth of specific crystalline facets. A controllable phase transition from Cu 1.29 Te to Cu 1.43 Te NCs is also demonstrated. The latter can be further converted into Cu 2 SnTe 3 and SnTe through Sn incorporation. Temperature dependent thermoelectric properties of metal (Cu and Sn) telluride nanostructure thin films are also studied, including Cu 1.29 Te, Cu 1.43 Te, Cu 2 SnTe 3 , and SnTe. Cu 2 SnTe 3 is a low carrier density semimetal with compensating electron and hole Fermi surface pockets. The engineering of crystal phase and morphology control of colloidal copper tin telluride NCs opens a path to explore and design new classes of copper telluride-based nanomaterials for thermoelectrics and other applications.

Bottom-Up Synthesis of SnTe-Based Thermoelectric Composites

“…At high enough Cu 1.5 Te concentrations, the formation of the Cu 2 SnTe 3 phase may also contribute to the charge transport by accepting electrons or facilitating the charge transport at the grain boundary. Notice in this regard that Cu 2 SnTe 3 is generally regarded as a low-carrier density semimetal . At the same time, the large grains generated in the presence of the Cu 2 SnTe 3 phase also contribute to the electrical conductivity but have little effect on the Seebeck coefficient …”

Synthesis and Performance of Large-Scale Cost-Effective Environment-Friendly Nanostructured Thermoelectric Materials

“…Yang et al used tellurium oxide as a tellurium precursor to synthesize monodispersed nanocrystals of another similar material Cu 2 SnTe 3 [58]. Yin et al [59] synthesized different nanostructures such as Cu 1.29 Te nanocubes, nanosheets, and nanorods; Cu 1.43 Te hexagonal nanoplates; SnTe nanorods; and Cu 2 SnTe 3 nanocubes by carefully controlling the amount of tin precursor and reaction temperature in a colloidal synthesis method. B. Xu et al reported low-temperature and scalable (ca.…”

Band Engineering-Tuned Localized Surface Plasmon Resonance in Diverse-Phased Cu2–xSySe1–y Nanocrystals

“…Cation-deficient (self-doped) metal chalcogenide nanocrystals (NCs) exhibiting localized surface plasmon resonance (LSPR) have been extensively investigated as an infrared-responsive light-harvesting material. − Cation-deficient copper chalcogenide NCs are typical members of the degenerately doped semiconductors family, − which have attracted significant attention owing to their potential applications in thermoelectric, light-emitting, photovoltaic devices and photocatalysis. , Because such degenerated semiconductors exhibit dual nature of metals and semiconductors, the interplay between LSPR and band engineering is an important research issue. Illustrating the association between band engineering and LSPR tuning in such degenerated copper chalcogenides holds a key to further modulation of the cation-deficient copper chalcogenide NCs for suitable applications.…”