Tailoring the Broadband Emission in All-Inorganic Lead-Free 0D In-Based Halides through Sb3+ Doping

All-inorganic lead-free metal halides doped with ns 2 -metal ions have shown great promise in optoelectronics and photovoltaics owing to their superior optical properties. Herein, a strategy is reported for tailoring the optical properties of 0D A 2 InX 5 ⋅H 2 O and A 3 InX 6 (A = Cs, Rb; X = Cl, Br) crystals via Sb 3+ doping, and the excited-state dynamics of Sb 3+ is unveiled through temperature-dependent photoluminescence (PL) and femtosecond transient absorption spectroscopies. Owing to the spatially confined 0D structure of the In-based halides, Sb 3+ ions experience a strong Jahn–Taller distortion on the excited state, which results in intense PL from Sb 3+ with a broad emission band and a large Stokes shift. Through the control of A cation and the octahedral unit, tunable Sb 3+ emissions (490−750 nm) with PL quantum yields up to 91.8% are achieved in these 0D In-based halides. These findings provide fundamental insights into the excited-state dynamics of Sb 3+ in 0D metal halides, thus laying a foundation for future design of luminescent lead-free 0D metal halides through ns 2 -metal doping towards versatile applications.