Improved thermoelectric performance of bilayer Bi2O2Se by the band convergence approach

Using first-principles calculations combined with Boltzmann transport theory, we investigate the effects of the interlayer distance on the electronic and phonon thermal transport properties of the bilayer Bi2O2Se. As the interlayer distance varies from 3.65 to 3.35 angstrom, the maximum power factors of 13-90 and 10-13 mu W cm(-1) K-2 are found for p-type and n-type doped bilayer Bi2O2Se, respectively. The figure of merit value of p-type doped bilayer Bi2O2Se is enhanced to 1.86 with an interlayer spacing of 3.35 angstrom at 300 K. At 800 K, it is as high as 5.9, which is much larger than the highest value of 3.35 for Bi2O2Se reported in the literature. This study thus demonstrates that structural dimension reduction and band convergence are effective methods for improving the thermoelectric performance of Bi2O2Se.