Publication date: 21st July 2025
Chiral organic–inorganic hybrid metal halides are emerging as a promising class of materials for spin-controlled optical and optoelectronic applications. Their lattice chirality can be tuned via the incorporation of enantiopure organic cations.1-3 However, materials crystallizing in enantiomorphic space groups, where the R- and S-configured structures are non-superimposable mirror images, remain rare. In my talk, I will present novel chiral zero-dimensional (0D) (R-/S-MBA)₂SnBr₆ (MBA = methylbenzylammonium) crystals with enantiomorphic helical space groups P6₅ (M-helix) and P6₁ (P-helix). The helicity of the inorganic framework arises from 60° helical rotational alignment along the six-fold screw axis, stabilized by strong N–H···Br and C–H···π interactions. This cooperative assembly induces long-range chirality in the lattice, supported by DFT calculations showing strong electronic coupling between MBA ligands and SnBr₆²⁻ units. The chiral crystals and thin films exhibit mirrored circular dichroism (CD) spectra with a relatively high gCD factor of 3.5 × 10⁻². Interestingly, the crystals does not the Cotton effect a rare phenomenon in chiral metal halides. Additionally, the materials demonstrate broadband second harmonic generation (SHG) from 875 to 1200 nm, with a dissymmetry factor (gCP–SHG) up to 0.44 under 1030 nm excitation. Alloying with Pb induces a structural transition to a non-helical chiral space group (P2₁2₁2₁), highlighting that helicity is intrinsic to specific metal–halide combinations. These results introduce a new family of chiral halides with unique linear and nonlinear optical activity, opening exciting opportunities in spin-optoelectronics and chiroptical photonics.
|
Figure 1. Helical crystal structures of (R-/S-MBA)₂SnBr₆ viewed along the b-axis. Blue helices are guides to the eye, illustrating the continuous propagation of chirality throughout the lattice. |
Keywords:
Chiral metal halides, enantiomorphic space group, helical framework, circular dichroism, second harmonic generation
This work has received funding from the Spanish Agencia Estatal de Investigación (AEI/MCIN) through grants: TED2021-131628A-I00, CNS2022-135531 and PID2023-147567NB-I00, funded by MICIU/AEI/10.13039/501100011033 and European Union Next Generation EU/PRTR.
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.