Effects of Ligand Chemistry on Ion Transport in 2D Hybrid Organic- Inorganic Perovskites

GC Wei and AB Kaplan and H Zhang and YL Loo and MA Webb, ADVANCED ENERGY MATERIALS, 14 (2024).

DOI: 10.1002/aenm.202401087

2D hybrid organic-inorganic perovskites are potentially promising materials as passivation layers that can enhance the efficiency and stability of perovskite photovoltaics. The ability to suppress ion transport is proposed as a stabilization mechanism, yet an effective characterization of relevant modes of halide diffusion in 2D perovskites is nascent. In light of this knowledge gap, molecular dynamics simulations with enhanced sampling and experimental validation to systematically characterize how ligand chemistry in seven (R-NH3)2PbI4 systems impacts halide diffusion, particularly in the out-of-plane direction is combined. It is found that increasing stiffness and length of ligands generally inhibits ion transport, while increasing ligand polarization generally enhances it. Structural and energetic analyses of the migration pathways provide quantitative explanations for these trends, which reflect aspects of the disorder of the organic layer. Overall, this mechanistic analysis greatly enhances the current understanding of halide migration in 2D hybrid organic-inorganic perovskites and yields insights that can inform the design of future passivation materials. This study leverages molecular dynamics simulation and experimental characterization to elucidate the effects of ligand chemistry on suppressing ion transport in 2D hybrid-inorganic perovskites. Analyses reveal that increasing stiffness and length of ligands generally inhibits ion transport, while increasing ligand polarization generally enhances it. These insights provide possible principles for designing passivation materials to enhance the stability of perovskite photovoltaics. image

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