The　relatively　lower　performance　of　n-type　legs　has　significantly　hindered　the　application　of　PbTe　materials　in　medium-temperature　thermoelectric　(TE)　power　generation,　underscoring　the　urgent　need　to　enhance　the　TE　performance　of　n-type　PbTe.　In　this　study,　electron-phonon　decoupling　was　achieved　through　the　precise　manipulation　of　a　single　copper-doping　element　in　PbTe　(i.e.,　Pb1.005-xCu2x+0.003Te),　enabling　the　concurrent　optimization　of　phonon　transport　and　electrical　properties.　High-content　Cu　doping　induced　substantial　lattice　strain　and　abundant　precipitates,　which　effectively　scattered　heat-carrying　phonons　and　significantly　reduced　lattice　thermal　conductivity.　Simultaneously,　the　retention　of　high　mobility　and　the　self-regulation　of　electron　concentration　improved　electrical　performance　across　a　broad　temperature　range.　As　a　result,　an　impressive　average　zT　of　1.3　was　achieved　from　523　to　823　K　in　n-type　Pb0.985Cu0.043Te.　Building　on　this,　a　seven-pair　TE　module　was　fabricated,　attaining　an　energy　conversion　efficiency　of　∼8　%　under　a　temperature　difference　of　420　K.　This　work　provides　fresh　insights　into　strategies　for　enhancing　the　TE　performance　of　n-type　PbTe.　©　2025