Dielectric Behavior as a Screen in Rational Searches for Overlooked Electronic Materials: Metal Pnictide Sulfosalts

Dielectric screening plays an important role in preventing carrier scattering and trapping by point defects for many semiconductors such as the halide perovskite solar materials. However, it was rarely considered as a screen to find new electronic semiconductors. We performed a material search study using the dielectric properties as a screen to identify potential electronic materials in the class of metal-pnictide ternary sulfosalts, containing Bi or Sb. We find significant cross-gap hybridization between the S p derived valence bands and pnictogen pderived conduction bands in many of the materials. This leads to enhanced Born effective charges, and highly enhanced dielectric constants. We find a chemical rule for high dielectric constant in terms of the connectivity of the structure. Through first principles screening, we find a series of compounds with low effective mass, high dielectric constant and other properties that suggest good performance as electronic materials, and also several potential thermoelectric compounds. The results illustrate the utility of dielectric properties as a screen for identifying complex semiconductors.