Charge bridge built between organic ligands and metal halides in OMHHs - Dr. Xujiie Lü

Organic-inorganic hybrid materials provide integrated platforms for modern technologies. Low-dimensional (low-D) organic metal halide hybrids (OMHHs) have emerged as promising materials for new-generation optoelectronic devices due to their integrated properties from organic and inorganic components. However, for most low-D OMHHs developed to date, especially the zero-D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents charge transfer at the hybrid interfaces and limits the tunability of their optical and electronic properties. A new study led by Dr. Xujiie Lü and a team of scientists from HPSTAR, reveals the underlying mechanisms at play and proposes techniques to overcome these challenges. Anomalous Charge Transfer from Organic Ligands to Metal Halides in Zero-Dimensional [(C₆H₅)₄P]₂SbCl₅ Enabled by Pressure-Induced Lone Pair-π Interaction is published in Angewandte Chemie International Edition.

Using pressure engineering, Dr. Lü et al. report spontaneously efficient charge transfer from organic ligands to metal halides in 0D OMHHs (Ph₄P)₂SbCl₅ leading to high emission with a 100% PLQY from self-trapped excitons. Combined in situ experimental diagnostics and theoretical simulations elucidate the underlying mechanisms. The pressure-induced strong coupling between the lone-pair electrons of Sb³⁺ and the π electrons of the benzene ring (lp-π interaction) serves as an unexpected “bridge” for the interfacial charge transfer. Such an lp-π interaction has never been reported in organic-inorganic metal halide materials. Furthermore, the pressure-induced transition of energy-level alignment from type-II to quasi-type-I provides the driving force for the charge transfer from ligands to metal halides, together resulting in the high emission with a 99% PLQY at the metal halides.

Caption: Pressure induced lone pair-π interaction and realize charge transfer from ligands to metal halides.

By manipulating the lp-π interactions in organic-inorganic hybrid systems, this work realizes an anomalously efficient charge transfer at the hybrid interface of 0D OMHHs, introducing a versatile strategy for the design and optimization of functional materials.