研究目的
To search for homovalent alternatives for A, B, and X-ions in ABX3 type inorganic halide perovskites suitable for tandem solar cell applications.
研究成果
From this study, a number of novel perovskite materials are found that can be used for photovoltaic applications. Eleven perovskite materials (2 Cs-based, 3 Rb-based, and 6 K-based) are identified as suitable for tandem solar cell applications. The study concludes that Ge-based perovskites have low power conversion efficiency (PCE) compared to other metals, but RbGeBr3 shows promising band gaps. No experimental evidence of the synthesis of Potassium-based halide perovskites has been found, but DFT studies suggest their potential for photovoltaic devices.
研究不足
The computational calculations come with certain inaccuracies, and a margin of 0.5 eV on both the high and low ends is kept to consider perovskites with band gaps between 0.5 eV and 2.5 eV. The experimental and simulated phases are different for most cases, leading to different lattice parameters, lattice angles, and bond lengths.
1：Experimental Design and Method Selection:
The study uses Density Functional Theory (DFT) methods for a systematic screening of inorganic halide perovskites. The geometry of the perovskites is optimized in all three phases (cubic, orthorhombic, and tetragonal) using the PBE exchange-correlation functional to find structures with the lowest potential energy. Band gaps are calculated using both PBE and HSE functionals, with spin-orbit coupling corrections due to the presence of heavy elements.
2：Sample Selection and Data Sources:
The study considers 45 perovskite materials, combining 3 inorganic cations (Cs, K, Rb), 5 metals (Cd, Hg, Ge, Pb, Sn), and 3 halogens (Cl, Br, I).
3：List of Experimental Equipment and Materials:
The Fritz-Haber Institute Ab-initio Molecular Simulations (FHI-AIMs) software package is used for DFT calculations.
4：Experimental Procedures and Operational Workflow:
Initial lattice parameters are given in supplementary information. Band gaps are first calculated using the PBE functional as a pre-screening criterion, followed by more accurate HSE functional calculations for materials that pass the pre-screening.
5：Data Analysis Methods:
The nature of the band gaps is understood by plotting the band structures of the materials. The Goldschmidt tolerance factor (GTF) is calculated to analyze phase stability.
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