Molecule intercalation molds supramolecular assembly of crowned octahedrons into extremely thermally-anomalous two-family hybrid semiconductors

The hybrid semiconductors interweaved by inorganic and organic building blocks have novel physical properties other than conventional pure organic or pure inorganic semiconductors. However, the underlying microscale mechanisms lying behind their special characteristics are unclear. Here, we unravel the angstrom-scale quantum mechanisms leading to the highly abnormal thermal and photonic behaviors of two distinct types of layered and nonlayered hierarchically inorganic–organic hybrid semiconductors. They are composed of hierarchically self-assembled frameworks of crown ether-sandwiched inorganic chloride octahedrons bound by small polar molecules. They exhibit rare extremely-anisotropic and lattice planes-sensitive thermal expansions when the temperature increases. The combined microstructural characterizations and density functional theory calculations reveal that the giant thermal anomaly arises from the hybrid-structure-determined strongly anisotropic angstrom-scale cohesion forces between the organic and inorganic compositional units. Actually, to one’s surprise, all kinds of forces, ionic, covalent, and hydrogen bonds as well as van der Waals force, play important roles and collaboratively bring strong anharmonicity in such hybrid semiconductors. The layered semiconductor crystals exhibit confusingly two orders of magnitude higher luminescence quantum yields compared with the nonlayered ones. The DFT calculation uncovers that this owes to the much bigger quantum transition rate caused by the crystal symmetry-determined higher degree of spatial overlap of the band-edge quantum orbitals in the layered semiconductor. These findings reveal how the angstrom-scale basic interactions bring unique thermal and photophysical properties of the novel hierarchically inorganic–organic hybrid semiconductors.

Huaxin Wu is a doctoral student at Southeast University, specializing in metal halide semiconductor materials. His main focus is on the photoelectric physical mechanisms of these materials, including spectral regulation, carrier dynamics, stability, and optimization of luminescence performance. Currently, he is dedicated to enhancing the luminescence efficiency and long-term stability of new metal halide semiconductors through material design and in-situ characterization, and developing white light-emitting semiconductor materials with potential applications.