Doping studies of alkali-metal rocksalt based I-V-VI$_2$ compounds with intrinsically minimal thermal conductivity

Past research has shown that rocksalt-based I-V-VI compounds have intrinsically low thermal conductivity as a result of the lone-pair electrons on the group V element. Theoretical calculations have revealed the presence marginally stable acoustic phonons which have extremely large Gr\"{u}neisen parameters. These result in a strong anharmonicity in heat-carrying acoustic phonon branches of select I-V-VI$_{2}$ compounds. Here, we extend this work to the electronic properties of the materials, which all have similar valence band structures. As a result of these two material properties, we are able to explore if the excellent zT observed in AgSbTe$_{2}$ extends to materials with cheaper starting elements and better high-temperature stability. Here we introduce new doping studies in I-V-VI$_{2}$ compounds where the group I element is an alkali-metal atom.