N-Type thermoelectric properties of a doped organoboron polymer

Abstract

Most of n-type thermoelectric polymers are based on electron-withdrawing building blocks containing amide or imide units. Organoboron polymers containing boron-nitrogen coordination bond represent a new kind of n-type thermoelectric polymers. In this manuscript, using (4-(1,3-Dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl) phenyl) dimethylamine (N-DMBI) as the n-dopant, we report the thermoelectric performance and stability of organoboron polymer (PBN-19) films. Compared to the tetrakis(dimethylamino)ethylene (TDAE) vapor doped PBN-19 film, the N-DMBI doped PBN-19 films show inferior thermoelectric performance but much enhanced stability. We find that sequential doping leads to better thermoelectric performance compared to blend doping for N-DMBI doped PBN-19 films. According to the microstructure analysis, in blend doped film, N-DMBI tended to form aggregates and could not dope PBN-19 efficiently. In comparison, in sequentially doped film, N-DMBI could enter into the PBN-19 film and dope PBN-19 to a higher level. The N-DMBI doped PBN-19 film shows a maximal electrical conductivity of 0.630 S cm−1 and a maximal power factor of 0.22 μW m−1 K−2.