Gradient Luminescence Enhancement in Organic Metal Halide Perovskites via the Suppression of [SbCl n ] 3- n Unit Distortion.

Intrinsic stereochemical activity of the 5s ² electron configuration in Sb ³⁺ leads to structural distortion within [SbCl _n ] ^{3- n} units, which, while stabilizing the material, paradoxically diminishes luminescence intensity due to induced asymmetry. To address this issue, a strategy, which encompasses increasing the structural dimensions and introducing In ³⁺ doping, was developed to mitigate the geometrical distortion in the [SbCl _n ] ^{3- n} units within the metal-organic perovskite (DABCO) ₂ Sb ₂ Cl ₁₀ ·H ₂ O and (DABCO) ₂ SbCdCl ₉ ·2H ₂ O (DABCO = triethylenediamine). This dimensional augmentation confines lattice distortion effectively, and the In ³⁺ doping modifies the 5s ² electron configuration of Sb ³⁺ , thereby reducing the distortion at its origin. The unique suitability of indium-based halides as a matrix for Sb ³⁺ doping is underscored by our approach, which capitalizes on their ability to regulate the electron configuration of Sb ³⁺ . This strategy has been validated through crystallographic data from single-crystal X-ray diffraction. By effectively reducing the adverse effects of geometric distortion, several hundred-fold enhancements in the luminescent intensity of the material have been achieved by our methodology, leading to potential applications in white-light LEDs. This advancement not only highlights the pivotal role of structural symmetry in the optical properties of materials but also exemplifies the power of material engineering to optimize the optical performance.