| The focus of this research is on the material challenges in photovoltaic. Copper Sulfide (Cu2S) has been regarded as a potential solar absorber materials in photovoltaic industry. Despite its simple composition, it is a complex material. Copper atoms are mobile in Cu2S crystals facilitating copper vacancies; hence promote Cu-deficient non-stoichiometric CuxS. Majority of the present work is directed towards understanding the stability issue related with Cu2S/CuxS. We used density functional theory systematically to predict acanthite like structure as ground state structure of Cu2S. The crystal structure of acanthite Cu2 S is much simpler than the experimentally observed low chalcocite, though electronic structures are similar with Cu-d showing high dominance in valence band. Theoretically we find that both structures show a tendency of forming Cu-vacancy. As it becomes p-type with Cu vacancy, band gap also increases. To understand about the effect of doping in Cu2S, tin and oxygen doping have been studied. |
