Antimony doping to enhance luminescence of tin(IV)-based hybrid metal halides

Lead-based organic–inorganic metal halides (OIMHs) have recently attracted special attention due to their efficient broadband photoluminescence. However, the toxicity of lead poses a challenge for their further development. Here, we selected Sn(IV) as the metal center to synthesize the environmentally friendly and stable luminescent OIMHs (C9H15N3)2SnCl8 and (C9H15N3)2SnBr8 (C9H13N3 is 1-(2-pyridyl)piperazine). Both compounds possess zero-dimensional structures, crystallizing in the monoclinic space group P21/c, and their optical band gaps were experimentally determined to be 3.19 and 2.60 eV, respectively. Under UV excitation at room temperature, (C9H15N3)2SnCl8 exhibited double-peak emissions centered at 405 and 688 nm, which were attributed to the organic cation and inorganic octahedra, respectively. Upon introducing 5s2-lone-pair-containing Sb3+ in (C9H15N3)2SnCl8, self-trapped emission was promoted, and the photoluminescence quantum yield increased from ∼1% to ∼17.84%. This work suggests effective strategies for finding environmentally friendly stable OIMHs and for further enhancing the luminescence properties through lone-pair-containing cation doping.