Sb³⁺ Doping-Induced Triplet Self-Trapped Excitons Emission in Lead-Free Cs₂SnCl₆ Nanocrystals

Doped halide perovskite nanocrystals (NCs) have opened new opportunities for the emerging optical and optoelectronic applications. Here, we describe a hot-injection synthesis of all-inorganic lead-free Cs₂SnCl₆ and Sb³⁺ doped Cs₂SnCl₆ NCs. Cs₂SnCl₆ NCs present a blue emission peak at 438 nm, whereas a new broad-band emission peak appears at 615 nm for the Sb³⁺ doped NCs. Comparative structural and spectral characterizations of Sb³⁺ doped Cs₂SnCl₆ NCs with micrometer-sized undoped and Sb³⁺ doped crystals show that the formation of broad-band orange emission is originted from triplet self-trapped excitons, attributed to the ³P-¹S₀ transitions (n = 0, 1, 2). Our results in Sb³⁺ doped Cs₂SnCl₆ materials provide insights into the machanisms of doping-induced emission centers, and it extends the existing knowledge of optical properties of doped halide NCs for further studies.