研究目的
Investigating the ion diffusion properties in lead-free halide double perovskites (HDPs) to understand their performance stability for optoelectronic applications.
研究成果
The study reveals that fast ion diffusion of dominant defects in HDPs may lead to performance instability. Ag ion diffusion through the self-interstitial mechanism has a much lower barrier compared to the vacancy-mediated mechanism. Applying an external compressive strain can effectively suppress the ion diffusion, enhancing the performance stability of HDPs.
研究不足
The study focuses on Cs2AgInX6 (X = Cl, Br) HDPs under Ag-rich conditions. The generality of the findings is substantiated by the investigation of other HDPs, but further experimental validation is needed.
1：Experimental Design and Method Selection:
The study employs first-principles calculations using density functional theory (DFT) with a plane-wave basis set and projector augmented wave (PAW) method. The exchange-correlation energy was treated with the generalized gradient approximation (GGA) in the Perdew-Burke-Ernzerhof (PBE) form and with the screened Heyd?Scuseria?Ernzerh (HSE06) hybrid density functional. The spin-orbit coupling (SOC) effect is included in all calculations.
2：Sample Selection and Data Sources:
Cs2AgInX6 (X = Cl, Br) HDPs are used as prototypes. A 160-atom supercell with a 1 × 2 × 2 Γ-centered k-mesh was employed during the PBE + SOC geometry optimizations.
3：List of Experimental Equipment and Materials:
The Vienna Ab initio Simulation Package (VASP) was used for the calculations.
4：Experimental Procedures and Operational Workflow:
The climbing image nudged elastic band (CI-NEB) method was employed to determine the diffusion barriers (ΔEa) and the migration paths for the most dominant defects.
5：Data Analysis Methods:
The defect formation energy and diffusion coefficients were calculated to analyze the ion diffusion properties.
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