Achieving Near‐unity Photoluminescence Quantum Yields in Organic‐Inorganic Hybrid Antimony (III) Chlorides with the [SbCl5] Geometry

Abstract Hybrid organic–inorganic antimony halides have attracted increasing attention due to the non‐toxicity, stability, and high photoluminescence quantum yield (PLQY). To shed light on the structural factors that contribute to the high PLQY, five pairs of antimony halides with general formula A 2 SbCl 5 and A 2 Sb 2 Cl 8 are synthesized via two distinct methods and characterized. The A 2 SbCl 5 type adopts square pyramidal [SbCl 5 ] geometry with near‐unity PLQY, while the A 2 Sb 2 Cl 8 adopts seesaw dimmer [Sb 2 Cl 8 ] geometry with PLQY≈0 %. Through combined data analysis with the literature, we have found that A 2 SbCl 5 series with square pyramidal geometry generally has much longer Sb⋅⋅⋅Sb distances, leading to more expressed lone pairs of Sb III . Additional factors including Sb−Cl distance and stability of antimony chlorides may also affect PLQY. Our targeted synthesis and correlated insights provide efficient tools to precisely form highly emissive materials for optoelectronic applications.