Relationship between the density of states effective mass and carrier concentration of thermoelectric phosphide Ag6Ge10P12 with strong mechanical robustness

Recent progress in phosphide materials for thermoelectric conversion

“…88 Hole doping using Ga in Ag 6 Ge 10−x Ga x P 12 is effective and can control the hole concentration, with some additional suppression of k L . 67 The m * DoS is rather large for Ag 6 Ge 10−x Ga x P 12 , between 8 and 16m e depending on the Fermi level, due to the combination of a low dispersion band in the G-F direction and the contribution of a lower energy valence band in the G-H direction. 67 The complex band structure and measured m * DoS values are illustrated in Fig.…”

“…In single crystal Ag 6 Ge 10 P 12 , k L ∼ 1.75 W m −1 K −1 is observed at 300 K, which is reduced to 1.3 W m −1 K −1 for polycrystalline samples, with lowest observed values ∼0.8 W m −1 K −1 in Ag 5.7 Cu 0.3 Ge 10 P 12 . 48,67,88 One explanation for the low k L is the weak interaction between the covalent Ge-P framework and the enclosed [Ag 6 Ge 4 ] clusters, in which large thermal displacement parameters give Ag + a liquid-like behaviour. 48 Alternatively, the [Ag 6 ] 4+ cluster has been considered to act as a low energy "rattler", leading to suppression of acoustic phonon modes and low sound velocities.…”

“…concentrations (n H ) and mobilities ( H ).CompositionType Band m* DoS (m e ) n H (cm -3 ) μ H (cm 2 V -1 s -1 ) Ag 6 Ge 10-x Ga x P 1267 p Multiple # 7.7-16.5 1.1-11 × 10 20 1.11-1.84 CaCuP 50, 68 p Γ (N v = 2) 1.0 1.6 × 10 20 101 MgCuP 50, 68 p Γ (N v = 1) 1.7 2.4 × 10 20 29 Cd 3 P 2-δ 55 n Γ (N v = 1) 0.09 3.6-10.5 ×10 17 950-1690 Cd 3 P 1-x As x 53, 54 n Γ (N v = 1) 0.05-0.11 6.1-28 × 10…”

Polymer and composite based thermoelectrics: Basics, scopes and issues

“…Here the density of states effective mass can also describe as m* DOS = N v 2/3 m b *, where Nv is the valley degeneracy and m b is the band effective mass of a single parabolic band. [ 25 ]…”

“…Here the density of states effective mass can also describe as m*DOS = Nv 2/3 mb*, where Nv is the valley degeneracy and mbis the band effective mass of a single parabolic band. [25] Table 1: The presence of a-conjugated chain is the first and most important prerequisite for a polymer to conduct. Conjugated polymers on the other hand, with band gaps ranging from 1 to 3 eV, [26] compete with semiconducting or even insulating characteristics.…”