  Compounds of low lattice thermal conductivity (LTC) are essential for seeking
thermoelectric materials with high conversion efficiency. Some strategies have
been used to decrease LTC. However, such trials have yielded successes only
within a limited exploration space. Here we report the virtual screening of a
library containing 54,779 compounds. Our strategy is to search the library
through Bayesian optimization using for the initial data the LTC obtained from
first-principles anharmonic lattice dynamics calculations for a set of 101
compounds. We discovered 221 materials with very low LTC. Two of them have even
an electronic band gap < 1 eV, what makes them exceptional candidates for
thermoelectric applications. In addition to those newly discovered
thermoelectric materials, the present strategy is believed to be powerful for
many other applications in which chemistry of materials are required to be
optimized.
