Improved thermoelectric performance of BiCuSeO by Ag substitution at Cu site

BiCuSeO oxyselenide-based thermoelectric materials are attracting much attention due to their ultra-low intrinsic thermal conductivity (ĸ) and moderate Seebeck coefficient (S). However, the low conversion efficiency limits their application in energy conversion systems. This paper investigated the effect of monovalent Ag-doping in BiCuSeO at Cu site in the presence of polyvinyl alcohol (PVA). The results show that Ag is effectively doped at Cu site. The heavy atom substitution in BiCu1−xAgxSeO at Cu site can enhance S and reduce its total thermal conductivity (k) by phonon scattering. Further, the incorporation of heavy atom (Ag) with different ionic radii results in the improved ZT of 0.64 for BiCu1−xAgxSeO, which is 16% more than that for pure BiCuSeO (ZT = 0.55) at 923 K. It is believed that the Cu site should be an efficient dopant site to improve the efficiency of oxyselenide-based thermoelectric materials

Enhanced thermoelectric efficiency of Cu2-xSe-Cu2S composite by incorporating Cu2S nanoparticles

The study of thermoelectric transport properties in Cu2-x Se and Cu2S has gained an importance in the thermoelectric research during last few years due to their superionic behavior and low cost. Here, we reported a facile method to enhance the thermoelectric efficiency of Cu2-x Se by introducing Cu2S nanoparticles (NPs) in the matrix of Cu2-x Se. The observed efficiency is a direct result of simultaneous improvement of Seebeck coefficient (S) because of the external strain induced by Cu2S nanoinclusions in Cu2-x Se and decline in the total thermal conductivity by suppressing both electronic and lattice thermal contributions. Such higher S and lower thermal conductivity is realized for a composite structure with 10wt% nanoinclusions of Cu2S which effectively contributed to higher ZT value of 0.90 at moderate temperature of 773K. Thus, it is believed that the proposed hybrid structure is a promising p-type thermoelectric material for mid-temperature range energy harvesting applications

Cd-doping a facile approach for better thermoelectric transport properties of BiCuSeO oxyselenides

BiCuSeO-based thermoelectric materials have spurred tremendous interest among the thermoelectric community due to their ultra-low thermal conductivity and relatively large Seebeck coefficient (S). In this work, we have reported the effect of Cd-doping at the Bi site, instead of the previously studied Cu site, on the thermoelectric performance of BiCuSeO by modifying the insulating layer. While maintaining good phase purity, Cd was successfully doped at the Bi site as confirmed by X-ray absorption fine structure spectroscopy. The Cd-doping substantially improves the electrical conductivity by a factor of 20 through bond anharmonicity at room temperature while increasing the Cd concentration over 5%. Further, the incorporation of the lighter atom at the Bi site creates phonon scattering centers and results in weak bonding between the layers, resulting in a remarkable perturbation of the local geometric and electronic structure. BiCuSeO with 5% Cd-doping maintains a large S and a high electrical conductivity up to 923 K and exhibits the highest power factor values (600 μW m-1 K-2 at 323 K and 447 μW m-1 K-2 at 923 K) and the largest ZT (0.98 at 923 K). Cd-doping at the Bi site in p-type thermoelectric BiCuSeO was shown to be a very good technique for improving the thermoelectric performance and could be extended to other thermoelectric materials to enhance the efficiency of thermoelectric devices for energy-harvesting

Enhanced Thermoelectricity in High-Temperature β‑Phase Copper(I) Selenides Embedded with Cu₂Te Nanoclusters

We report remarkably enhanced thermoelectric performance of Te doped Cu₂Se in midtemperature range. Through ball-milling process followed by spark plasma sintering (SPS), nanoscale Cu₂Te clusters were embeded in the matrix of Cu₂Se, inducing a drastic enhancement of thermoelectric performance by reducing the thermal conductivity without degrading the power factor. A large <i>ZT</i> value of 1.9 was achieved at 873 K for Cu₂Se_1.9Te_0.1, which is about 2 times larger than that of the pure Cu₂Se. The nanoscale heat management by Cu₂Te nanoclusters in superionic conductors opens up an avenue for thermoelectric materials research