Doping for higher thermoelectric properties in p-type BiCuSeO oxyselenide

Abstract

The low power factor (PF) of BiCuSeO oxyselenide inhibits further improvement on thermoelectric figure of merit in the moderate temperature range. In this Letter, we show that the electron transport properties of doped BiCuSeO oxyselenide can be accurately described in acoustic phonon scattering assumption within the framework of single parabolic band model. It is further found that the doping elements alter the electron transport properties by tuning the effective mass and deformation potential. Based on these understandings, we argue that the higher power factor can be achieved by choosing the doping element based on reducing deformation potential coefficient and decreasing effective mass.

Enhanced Thermoelectric Properties of Pb‐doped BiCuSeO Ceramics

“…The 8% Pb-doped sample has a conductivity of ≈600 S cm −1 at room temperature, nearly two times higher than that for the 7.5% Ba-doped sample (≈350 S cm −1 ), [ 19 ] three times higher than the 7.5% Sr doping (≈200 S cm −1 ), [ 18 ] and 60 times higher than the 7.5% Mg doping (≈10 S cm −1 ). [ 14 ] It is generally believed that the electrical performance of a thermoelectric semiconductor depends primarily on the weighted mobility, [ 24 ] μ ( m *) 3/2 , which includes both the density-of-states effective mass ( m *) and the nondegenerate mobility ( μ ) of carriers. The effective mass is obtained by calculating the reaching a relatively high value ∼ 5 cm 2 /Vs.…”

“…The lattice thermal conductivity κ l could be somewhat reduced by increasing phonon scattering through the use of mass fl uctuation, [ 10 ] grain boundaries, [ 11 ] complex crystal structures, [ 12 ] or nanocomposites. [ 13 ] To enhance the ZT values of these high-temperature TE oxides further, compounds with intrinsically low thermal conductivity and good electric conductivity are highly desirable.Most recently, BiCuSeO oxyselenides [14][15][16][17][18][19] have been reported to exhibit low intrinsic thermal conductivity and tunable electric properties. BiCuSeO comprises (Cu 2 Se 2 ) 2− layers alternately stacked with (Bi 2 O 2 ) 2+ along the c axis of a tetragonal cell.…”

Copper chalcogenide thermoelectric materials

“…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]…”

EXAFS study of thermoelectric BiCuOSe: Effects of Cu vacancies

“…The pristine BiCuOSe shows p-type semiconductivity with a narrow band gap, yet fair carrier concentration and mobility [4]. Rational chemical approaches such as aliovalent cation substitutions, introduction of Cu vacancies or replacement of Se with Te could effectively enhance the electrical conductivity [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. At the same time, thanks to the mixed heavy and light bands in the upper valence band, the Seebeck coefficient of heavily-doped BiCuOSe may remain decent.…”