Pressure-induced enhancement of thermoelectric power factor in pristine and hole-doped SnSe crystals

摘要: We evaluate the influence of pressure on thermoelectric power factors PF ≡ S2σ pristine and Na-doped SnSe crystals by measuring their electrical conductivity σ(T) Seebeck coefficient S(T) up to ∼22 kbar with a self-clamped piston-cylinder cell. For both cases, is enhanced while reduced increasing as expected, but imbalanced variations lead monotonic enhancement under pressure. SnSe, σ(290 K) increases ∼4 times from ∼10.1 38 S cm−1, S(290 decreases only ∼12% 474 415 μV K−1, leading about three-fold 2.24 6.61 μW cm−1 K−2, which very close optimal value above structural transition at ∼800 K ambient In comparison, 290 moderately ∼30% 20 kbar. contrast, isostructural black phosphorus simple band structure was found decrease The comparison indicates that multi-valley valence beneficial for retaining large Our results also provide experimental confirmation previous theoretical prediction high can be used optimize efficiency SnSe.