Colloidal Sb³⁺-Doped Cs₂InCl₅·H₂O Perovskite Nanocrystals with Temperature-Dependent Luminescence

Abstract

Bulk crystals of Sb³⁺-doped A2InX₅·H₂O (A = Cs, Rb; X = Cl, Br) zero-dimensional (0D) perovskites exhibit a high photoluminescence (PL) quantum yield. Can we prepare their colloidal nanocrystals (NCs)? Such solution-processed nanocrystals will be useful for ink-based and thin-film technologies. Here, we present a facile route to synthesize colloidal Sb³⁺-doped Cs₂InCl₅·H₂O NCs and explore their optical properties. Sb³⁺ ions with 5s² outermost electrons yield intense (quantum yield 39%) green light emission. Temperature-dependent (6.5–300 K) PL provides a mechanistic origin of the excitation and emission processes. At room temperature, the undoped NCs emit blue light (2.8 eV, 435 nm) through localized defects, but below 200 K, near band-edge UV–blue emission (3.15 eV, 394 nm) is observed. Sb³⁺ doping introduces a new transition from relaxed excited ³P₁^* to ¹S₀ state yielding green emission with a long (1.94 μs) lifetime. Colloidal Sb³⁺-doped Cs₂InCl₅·H₂O NCs emitting intense green light along with a large Stokes shift and a long PL lifetime have potentials for solution-processed light-emitting applications