Bright yellow emission from self-trapped exciton in a new antimony chloride-based hybrid material [C8H10N3]2SbCl5

Single crystals of a hybrid organic/inorganic material (HOIM) with the formula [C₈H₁₀N₃]₂SbCl₅ were synthesized and characterized using X-ray diffraction, optical absorption, and photoluminescence spectroscopy. The crystal structure is composed of discrete [SbCl₅] units surrounded by organic (C₈H₁₀N₃) molecules, thus creating a zero-dimensional structure. For optical investigations, thin films have been prepared by spin-coating from the methanol solution of the compound. A strong yellow photoluminescence at room temperature, attributed to self-trapped excitons confined in isolated [SbCl₅]²⁻ square pyramids, is observed around 560 nm (2.21 eV) with the CIE chromaticity coordinates of (0.422, 0.534) and exciton binding energy of around 53 meV. This material shows an important photoluminescence quantum yield (PLQY) of ≈82 %. To further explore the electronic structure properties of the titled compound, Density Functional Theory (DFT) and time-dependent TD-DFT calculations were performed. A considerable correlation was observed between the theoretical results and the experimental data. This agreement is confirmed through the superposition of the experimental and theoretical absorption spectra. This calculation allowed us to plot the density of states (DOS) and determine the band gap of this material. This research successfully resulted in the development of a luminescent material with significant potential for applications in the field of photoluminescent technologies.