Revealing the Structure-Luminescence Relationship in Robust Sn(IV)-Based Metal Halides by Sb³⁺ Doping

Low-dimensional hybrid metal halides are an emerging class of materials with highly efficient photoluminescence (PL), but the problems of poor stability remain challenging. Sn(IV)-based metal halides show robust structure but exhibit poor PL properties, and the structure-luminescence relationship is elusive. Herein, two Sn(IV)-based metal halides (compounds 1 and 2) with the same constituent ((C₆H₁₆N₂)SnCl₆) but different crystal structures have been prepared, which however show poor PL properties at room temperature due to the absence of active ns² electrons. To improve materials' PL properties, Sb³⁺ with active 5s² electrons was embedded into the lattice of Sn⁴⁺-based hosts. As a result, efficient emissions were achieved for Sb³⁺-doped compounds 1 and 2 with a maximum PL efficiency of 14.28 and 62%, respectively. Experimental and calculation results reveal that the smaller distorted lattice structure of the host could result in the blueshift of the emission from Sb³⁺. Thus, a tunable color from red to orange was realized. Benefiting from the broadband efficient emission from Sb³⁺-doped compound 2, an efficient white light-emitting diode with a high color rendering index of up to 92.3 was fabricated to demonstrate its lighting application potential. This work promotes the understanding of the influence of robust Sn(IV)-based host lattice on the PL properties of Sb³⁺, advancing the development of environmentally friendly, low-cost, and high-efficiency Sn(IV)-based metal halides.