  Here we report further investigation on the thermodynamic, and transport
properties, and the first assessment of theoretical calculations for the
BiS2-layered Bi3O2S3 superconductor. The polycrystalline sample is synthesized
with the superconducting transition temperature of Tc_onset = 5.75 K, that
drops to 3.3 K by applying hydrostatic pressure of 6 kbar. Density-of-states
calculations give substantial hybridization between Bi, O and S, with the
largest Bi component at DOS, which supports the idea that BiS2 layer is
relevant for producing electron-phonon coupling. The electron charge carrier
concentration of only 1.5 x 10^19 cm-3 for Bi3O2S3 is additionally suggestive
of strong electron-phonon interaction in Bi-O-S system. The analysis of Seebeck
coefficient results strongly suggests that Bi3O2S3 is a semimetal. In fact, the
semimetallic or narrow band gap behavior may be general in the BiS2-layered
class of materials, including that of Bi4O4S3.
