Deqiang Yin1 Chaochao Dun2 David Carroll2 Mark Swihart1

1, University at Buffalo SUNY, Buffalo, New York, United States
2, Wake Forest University, Winston-Salem, North Carolina, United States

Tin chalcogenides have shown promise in applications including energy storage, optoelectronics, photovoltaics, and thermoelectrics. Here, we present a colloidal synthesis strategy to produce tin chalcogenide nanocrystals (NCs) with controllable stoichiometry, vacancies, shape, and crystal structure. Compared with previously reported methods, we use less expensive precursors, such as tin(IV) chloride and sulfur or selenium powder to produce tin (II, IV) chalcogenide NCs. By varying the anion precursors and ligands, we produced tin chalcogenides with different Sn valences, and modified the NCs morphology and size. We prepared nanostructured thin films of these materials by spin-coating, followed by post-treatment to study their thermoelectric properties. Room temperature Seebeck coefficients of -150 μV/K, -126 μV/K, 115 μV/K, 85 μV/K, and 154 μV/K were measured for SnS2, SnSe2, SnS, SnSe, and SnTe films. The SnTe thin film with high electrical conductivity and Seebeck coefficient was tested at different temperatures, showing that both electrical conductivity and Seebeck coefficient increase with increasing temperature. This work provides experimental evidence showing the promise of these tin chalcogenide NCs as thermoelectric thin film materials