Bulk assembly of a 0D organic antimony chloride hybrid with highly efficient orange dual emission by self-trapped states

Abstract

Low-dimensional organic–inorganic hybrid metal halides have drawn intense attention due to their flexible structures and outstanding optical properties. However, the toxicity of lead halides hinders their future application in optoelectronic devices. Herein, we report a zero-dimensional (0D) lead-free compound of (TPA)₂SbCl₅ (TTA⁺ = tetrapropylammonium cation) single crystals (SCs), which crystallizes in a triclinic system with P symmetry. Interestingly, (TPA)₂SbCl₅ exhibits a single broad orange emission band at 610 nm under low-energy excitation (e.g., 375 nm) with a high photoluminescence quantum yield (PLQY) of 95.3%, while it shows a dual-band emission profile with an additional narrow emission band at 466 nm at high-energy excitation (e.g., 300 nm), which is formed by the transformation of the doublet of spin–orbit interactions into two individual STEs. The Raman spectra supplied clear evidence for the self-trapped exciton (STE) with clear multiphonon modes in (TPA)₂SbCl₅, which reflects its strong nonlinear electron–phonon coupling. The emission mechanism for the temperature-dependent dual emission can be attributed to the radiative transitions of singlet STEs and triplet STEs in [SbCl₅]²⁻ clusters. Moreover, a white-light-emitting diode (WLED) was also fabricated by mixing (TPA)₂SbCl₅ with green (Ba₂SiO₄:Eu²⁺) and blue (BaMgAl₁₀O₁₇:Eu²⁺) phosphors, which exhibited CIE coordinates of (3.48, 3.50), a correlated color temperature (CCT) of 4900 K, and a color rendering index (CRI) of 93.2. Our achievements illustrate that the lead-free compound of (TPA)₂SbCl₅ has great potential in solid-state lighting.