No abstract

All‐inorganic lead‐free metal halides doped with ns2‐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 A2InX5⋅H2O and A3InX6 (A = Cs, Rb; X = Cl, Br) crystals via Sb3+ doping, and the excited‐state dynamics of Sb3+ is unveiled through temperature‐dependent photoluminescence (PL) and femtosecond transient absorption spectroscopies. Owing to the spatially confined 0D structure of the In‐based halides, Sb3+ ions experience a strong Jahn–Taller distortion on the excited state, which results in intense PL from Sb3+ with a broad emission band and a large Stokes shift. Through the control of A cation and the octahedral unit, tunable Sb3+ 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 Sb3+ in 0D metal halides, thus laying a foundation for future design of luminescent lead‐free 0D metal halides through ns2‐metal doping towards versatile applications.

Currently, lanthanide (Ln 3 + )-doped near-infrared (NIR)-emitting double perovskites (DPs) suffer from low photoluminescence quantum yield (PLQY). Herein, we develop a new class of NIR-emitting DPs based on Ln 3 + -doped Cs 2 (Na/Ag)BiCl 6 . Benefiting from the Na + -induced breakdown of local site symmetry in the Cs 2 AgBiCl 6 DPs, effective NIR emissions of Ln 3 + are realized through Bi 3 + sensitization. Specifically, 7.3-fold and 362.9-fold enhanced NIR emissions of Yb 3 + and Er 3 + are achieved in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs relative to those in Na-free Cs 2 AgBiCl 6 counterparts, respectively. The optimal absolute NIR PLQYs for Yb 3 + and Er 3 + in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs are determined to be 19.0 % and 4.3 %, respectively. Raman spectroscopy and first-principles density functional theory calculations verify the sublattice distortion in Cs 2 (Na/Ag)BiCl 6 DPs via Na + doping. These findings provide fundamental insights into the design of efficient NIR-emitting Ln 3 + -doped DPs for versatile optoelectronic applications.