Boost thermoelectric properties of n-type PbSe:Ag2Se:Ag in the vicinity of the percolation threshold

We study the microstructure and thermoelectric performance of n -type (PbSe) 100-x- y :(Ag 2 Se) x :(Ag) y ( x = 0 − 6, y = 0–28) films. For the (PbSe) 71 :(Ag 2 Se) 5 :(Ag) 24 , the carrier concentration enhanced in the vicinity of the percolation threshold. The high carrier concentration leads to a large average PF avg at the low temperature range of 300−523 K, the maximum PF avg for (PbSe) 100-x- y :(Ag 2 Se) x :(Ag) y samples is ∼37.83 μW cm −1 K −2 , which is about 200% higher than that of pure PbSe films (∼19.16 μW cm −1 K −2 ). In addition, PbSe:Ag 2 Se:Ag grain boundary and edge dislocation can engender intrinsically low thermal conductivity . The low thermal conductivity leads to a high zT and the maximum zT values for (PbSe) 71 :(Ag 2 Se) 5 :(Ag) 24 samples is ∼0.63 at room temperature, which is more than 250% higher than that of pure PbSe films ( zT = 0.25). A significant enhancement of thermoelectric performance in n -type (PbSe) 100-x-y :(Ag 2 Se) x :(Ag) y ( x = 0 − 6, y = 0–28) films was achieved at low temperature. For the (PbSe) 71 :(Ag 2 Se) 5 :(Ag) 24 , the carrier concentration enhanced from 2.36 × 10 19 cm −3 to 7.45 × 10 19 cm −3 in the vicinity of the percolation threshold. The high carrier concentration leads to a large average PF avg at the low temperature range of 300−523 K, the maximum PF avg for (PbSe) 100-x-y :(Ag 2 Se) x :(Ag) y samples is ∼37.83 μW cm −1 K −2 , which is about 200% higher than that of pure PbSe films (∼19.16 μW cm −1 K −2 ).