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

Abstract

We study the microstructure and thermoelectric performance of n-type (PbSe)100-x-y:(Ag2Se)x:(Ag)y (x = 0 − 6, y = 0–28) films. For the (PbSe)71:(Ag2Se)5:(Ag)24, the carrier concentration enhanced in the vicinity of the percolation threshold. The high carrier concentration leads to a large average PFavg at the low temperature range of 300−523 K, the maximum PFavg for (PbSe)100-x-y:(Ag2Se)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:Ag2Se: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:(Ag2Se)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).