I am studying MoS2 monolayer using DFT calculations. In one of my findings, band gap of a material after doping with an atom reduced. Does lesser band gap signify less stability ?
the stability of a given structure or material after doping with a given atoms type can be tested throught the formation energy of the dopant and not by comparing the band gap change. The formation energy will give you an idea about the stability and the solubility of these atoms.