Two-dimensional WSe2/SnSe p-n junctions secure ultrahigh thermoelectric performance in n-type Pb/I Co-doped polycrystalline SnSe

In this study, we, for the first time, introduce p-type two-dimensional (2D) WSe2 nanoinclusions in n-type Pb/I co-doped SnSe matrix to form WSe2/SnSe p-n junctions. These junctions act as energy barriers and effective phonon scattering sources, leading a high figure-of-merit (ZT) of ?1.35 at ?790 K polycrystalline SnSe. First-principles density functional theory calculation results indicates that I-doping shifts Fermi level up into conduction bands SnSe, making system behavior, while both Pb I dopants point-defect-based short-wavelength centers. The introduced 2D induce high-density interfaces junctions, which block electron carriers rationally tune carrier density, contributing absolute Seebeck coefficient ?470.7 ?V K-1 power factor ?5.9 ?W cm-1 K-2. Meanwhile, dense phase boundaries considerable lattice strains by significantly strengthen mid- long-wavelength scattering, giving rise much low thermal conductivity 0.35 W m-1 turn ZT ?1.35. This study provides new strategy achieve thermoelectric performance