Ambient Scalable Synthesis of Surfactant-Free Thermoelectric CuAgSe Nanoparticles with Reversible Metallic-n-p Conductivity Transition

Abstract

Surfactant-free CuAgSe nanoparticles were successfully synthesized on a large scale within a short reaction time via a simple environmentally friendly aqueous approach under room temperature. The nanopowders obtained were consolidated into pellets for investigation of their thermoelectric properties between 3 and 623 K. The pellets show strong metallic characteristics below 60 K and turn into an n-type semiconductor with increasing temperature, accompanied by changes in the crystal structure (i.e., from the pure tetragonal phase into a mixture of tetragonal and orthorhombic phases), the electrical conductivity, the Seebeck coefficient, and the thermal conductivity, which leads to a figure of merit (ZT) of 0.42 at 323 K. The pellets show further interesting temperature-dependent transition from n-type into p-type in electrical conductivity arising from phase transition (i.e., from the mixture phases into cubic phase), evidenced by the change of the Seebeck coefficient from -28 μV/K into 226 μV/K at 467 K. The ZT value increased with increasing temperature after the phase transition and reached 0.9 at 623 K. The sintered CuAgSe pellets also display excellent stability, and there is no obvious change observed after 5 cycles of consecutive measurements. Our results demonstrate the potential of CuAgSe to simultaneously serve (at different temperatures) as both an n-type and a p-type thermoelectric material.Keywords surfactant, free, thermoelectric, cuagse, nanoparticles, synthesis, reversible, ambient, metallic, n, p, conductivity, transition, scalable Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsHan, C., Sun, Q., Cheng, Z. Xiang., Wang, J. Li., Li, Z., Lu, G. & Dou, S. Xue. (2014 Supporting Information PlaceholderABSTRACT: Surfactant-free CuAgSe nanoparticles were successfully synthesized on a large scale within a short reaction time via a simple environmentally friendly aqueous approach under room temperature. The nanopowders obtained were consolidated into pellets for investigation of their thermoelectric properties between 3 K and 623 K. The pellets show strong metallic characteristics below 60 K and turn into an n-type semiconductor with increasing temperature, accompanied by changes in the crystal structure (i.e. from the pure tetragonal phase into a mixture of tetragonal and orthorhombic phases), the electrical conductivity, the Seebeck coefficient, and the thermal conductivity, which leads to a figure of merit (ZT) of 0.42 at 323 K. The pellets show further interesting temperature-dependent transition from n-type into p-type in electrical conductivity arising from phase transition (i.e. from the mixture phases into cubic phase), evidenced by the change of the Seebeck coefficient from -28 µV/K into 226 µV/K at 467 K. The ZT value increased with increasing temperature after the phase transition and reached 0.9 at 623 K. The sintered CuAgSe pellets also display excellent stability, and there is no obvious change observed after 5 cycles of consecutive measurements. Our r...

Robust scalable synthesis of surfactant-free thermoelectric metal chalcogenide nanostructures

“…The good agreement with the literature values supports the high purity of our metal chalcogenide nanostructures. [49][50][51][52][53][54][55][56][57] The size and morphology of the metal chalcogenide nanostructures are characterized by TEM in Figure 3. The particle size distribution of each sample, counted from 200 particles, is presented in Figure S5.…”

Lead-free SnTe-based thermoelectrics: enhancement of thermoelectric performance by doping with Gd/Ag

“…1 The thermoelectric conversion efficiency is governed by the gure of merit (ZT) dened as ZT ¼ a 2 sT/(k lat + k el ), where a, s, T, k lat and k el denote the Seebeck coefficient, electrical conductivity, absolute temperature, lattice thermal conductivity and electronic thermal conductivity, respectively. 2,3 Signicant improvement in the power factor (a 2 s) coupled with low lattice thermal conductivity is necessary for enhancing the performance of present thermoelectric materials. An approach to obtaining high power factors involves manipulation of the density of states through band engineering, including band convergence/degeneracy [4][5][6] or introduction of resonant impurity levels near the Fermi level.…”

Ambient Synthesis of One‐/Two‐Dimensional CuAgSe Ternary Nanotubes as Counter Electrodes of Quantum‐Dot‐Sensitized Solar Cells

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“…For example, surfactant-free CuAgSe nanoparticles were prepared on a large scale to show the temperature-dependent reversible transition of metallic n-p conductivity, and great potential in converting heat into electricity through the Seebeck effect. [14] Both dendritic and tubular CuAgSe were prepared from Ag 2 Se/Ag or Ag 2 Se/Se templates, [6,15] but it was time consuming and difficult to avoid Ag or Se in the final products. Thus, a facile and efficient method for the synthesis of ternary CuAgSe nanomaterials with well-defined composition and architecture is desirable.…”