An Ab initio Perspective on the Key Defects of CsCu5Se3, a Possible Material for Optoelectronic Applications

We report herein a study of the native point defects of a newly synthesized chalcogenide material, CsCu5Se3, using an ab initio approach (DFT + U, hybrid functional) to assess the electronic properties of the material through the supercell approach. The complex stability domain of this compound is investigated, and defect formation enthalpies are calculated with respect to the synthesis conditions. It shows that the layered structure of this compound is very prone to cationic vacancies, leading to a very pronounced p-type behavior. Depending on the conditions, V-Cs or V-Cu defects are the majority defects in the material and both play the role of acceptors. Chalcogen vacancies V-Se are always much less concentrated than cationic vacancies, despite being sometime quite low in enthalpy. The calculated interstitial defects are negligible. Defect concentrations with respect to crystal growth temperature were also simulated and rise up to a concentration of approximate to 10(21) cm(-3) for the majority defect above 500 K.