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

Abstract

We report herein a study of the native point defects of a newly synthesized chalcogenide material, CsCu 5 Se 3 , 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 behaviour. 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 10 21 cm −3 concentration for the majority defect above 500 K.

Exploring the Intrinsic Point Defects in Cesium Copper Halides

“…It is interesting to note that, both under halide X-rich (B) and X-poor conditions (D), the interstitials X i have the lowest formation energies, and therefore, they are the dominant defects. To further evaluate the intrinsic defect concentration, c i , at room temperature ( T = 300 K), the Boltzmann distribution e –Δ E f / k B T was used, where Δ E f is the formation energy of defect, k B is the Boltzmann constant, and T is temperature . Conventionally, for intrinsic defects, a larger value of c i means a higher defect concentration (the calculated values are reported in Table S5).…”

Ab Initio Study of the Thermodynamics of Intrinsic Point Defects in Thermoelectric Oxychalcogenide BiCuSeO

“…We have considered 11 compounds as possible competing phases to BiCuSeO during the synthesis (see Supporting Information). For each relative chemical potential of oxygen, the domain of existence of BiCuSeO can be represented with stability diagrams − in terms of the relative chemical potential of copper and bismuth (the value of Δμ Se is fixed by the three others in eq ). In these diagrams, straight lines correspond to the equality case of the condition while maintaining eq as valid and correspond to coexistence of both BiCuSeO and its competing phase.…”

First-principles calculations to identify key native point defects in Sr4Al14O25

“…Indeed, ab initio methods can be used to estimate the formation energy of point defects, and to determine their impact on the electronic structure of the ideal material. [20][21][22][23][24][25][26][27][28][29][30][31] Surprisingly, from our knowledge, such kind of simulations have not been reported for the Sr 4 Al 14 O 25 compound yet. Herein, we propose to fill this lack by characterizing more than 30 possible intrinsic point defects in this material and to identify the prominent expected ones versus specific synthesis conditions.…”