Synergistically Optimizing Electrical and Thermal Transport Properties of BiCuSeO via a Dual‐Doping Approach

Abstract

The layered oxyselenide BiCuSeO system is known as one of the high‐performance thermoelectric materials with intrinsically low thermal conductivity. By employing atomic, nano‐ to mesoscale structural optimizations, low thermal conductivity coupled with enhanced electrical transport properties can be readily achieved. Upon partial substitution of Bi3+ by Ca2+ and Pb2+, the thermal conductivity can be reduced to as low as 0.5 W m−1 K−1 at 873 K through dual‐atomic point‐defect scattering, while a high power factor of ≈1 × 10−3 W cm−1 K−2 is realized over a broad temperature range from 300 to 873 K. The synergistically optimized power factor and intrinsically low thermal conductivity result in a high ZT value of ≈1.5 at 873 K for Bi0.88Ca0.06Pb0.06CuSeO, a promising candidate for high‐temperature thermoelectric applications. It is envisioned that the all‐scale structural optimization is critical for optimizing the thermoelectricity of quaternary compounds.

Enhanced thermoelectric performance through grain boundary engineering in quaternary chalcogenide Cu2ZnSnSe4

“…5,6 On the other hand, structural manipulations have been adopted to suppress the thermal conductivity, such as introducing nanoscale structures to reduce the phonon mean free path, point defect scattering through alloying with other elements, and lone pair electron to develop soft phonon modes. [7][8][9][10][11] As the thermoelectric transport characteristics depend on interrelated material properties, 4 simultaneous enhancement of the power factor and decrease of the thermal conductivity are challenging. 15 Besides, CZTSe nanocrystals with relatively low thermal conductivity showed that the maximum zT is 0.44 at 723K for CZTSe 16 and 0.7 at 723K for Cu 2.1 Zn 0.9 SnSe 4 .…”

Copper chalcogenide thermoelectric materials

“…The zT of BiCuSeO has been increased to~1.5 through various approaches (see Fig. 17 b-f) including element doping (Mg, Sr, Ca, Ba, Pb at Bi site, Cu vacancies) [51,53,59,165,166], alloying (S, Te) [167], modulation doping [57] and texture treatment [56]. The findings and design methodology of this material are of valuable significance to investigation on similar layered compounds such as SnSe.…”

“…3a, Cu 2 Se possesses two sublattices: the rigid FCC framework of Se atoms and the disordered and flowing sublattice of Cu. At high temperatures, Cu ions migrate from one site (interstitial one formed by Se) to another, exhibiting a flowing character that is Figure 1 Timeline of zT for selected Cu-based superionic conductors [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] (red), tetragonal [28][29][30][31][32][33][34][35][36][37] (blue) and distorted [38][39][40][41][42][43][44][45][46][47][48][49] (green) diamond-like materials and BiCuSeO oxyselenides (purple) [50][51][52][53][54][55][56][57][58][59]…”

Metal oxides for thermoelectric power generation and beyond

“…Recently, Pb/Ca co-doping has been reported as an efficient way to enhance the TE properties of BiCuSeO [17,58]. Under Pb/Ca co-doping, the PF of BiCuSeO has reached 10 × 10 −4 W/mK 2 at room temperature [58].…”