Ionic 2D Materials for Designable Organic-Inorganic Interfaces

Summary

This project aims to establish ionic 2D materials as a class of tailored new compounds with systematically tuneable properties like chirality, ferroelectricity and permanent electric dipole moments and to investigate the interfaces that can be created between these materials and transition metal dichalcogenides (TMDCs), as well as other 2D materials studied in the SFB. The basic concept of combining amphiphilic organic cations with inorganic anions into molecularly thin layers is well established in biochemistry as the building principle of cell membranes. We transfer this approach to the chemistry of functional organic cations and different types of metalate anions. Through the judicious choice of the organic and inorganic components, this allows us to prepare 2D materials featuring desired specific and unique property combinations.

This versatile class of designer compounds adds additional functionalities to TMDCs when both are assembled into layered heterostructures. For example, a 2D ferroelectric with a permanent, switchable dipole moment can be combined with TMDCs to explore the effect of the permanent dipole moment in the ionic 2D material on the properties of TMDC monolayers. Potentially, this can act as a pseudo-spin injector for valleytronics. Tailoring the band gap energies and potentially even the work functions of the ionic 2D materials allows that different types of band alignment with TMDCs and hence controlling or optimising the injection efficiencies across the newly designed interfaces.

Project-related publications

1. N. Dehnhardt, M. Axt, J. Zimmermann, M. Yang, G. Mette, J. Heine
   Band Gap-Tunable, Chiral Hybrid Metal Halides Displaying Second-Harmonic Generation
   Chem. Mater. 32, 4801 (2020).
2. J. Möbs, M. Gerhard, J. Heine
   (HPy)₂(Py)CuBi₃I₁₂, a low bandgap metal halide photoconductor
   Dalton Trans. 49, 14397 (2020).
3. P. Klement, N. Dehnhardt, C.‐D. Dong, F. Dobener, S. Bayliff, J. Winkler, D.M. Hofmann, P.J. Klar, S. Schumacher, S. Chatterjee, J. Heine
   Atomically Thin Sheets of Lead‐Free 1D Hybrid Perovskites Feature Tunable White‐Light Emission from Self‐Trapped Excitons
   Adv. Mater. 33, 2100518 (2021).