Dual-Band Luminescent Lead-Free Antimony Chloride Halides with Near-Unity Photoluminescence Quantum Efficiency

Abstract

Low-dimensional organic−inorganic metal halide hybrids (OIMHs) with an ultrabroad-band emission are promising as downconversion phosphors for solid-state lighting. However, toxicity of Pb and low photoluminescence quantum efficiency (PLQE) hamper their application. Herein, two zero-dimensional (0D) lead-free organic antimony (Sb) chloride (Cl) hybrids with dual-band emissions and PLQEs: (TTA) 2 SbCl 5 (TTA = tetraethylammonium) and (TEBA) 2 SbCl 5 (TEBA = benzyltriethylammonium) are reported. Both compounds show a single broad-band orange emission with a near-unity PLQE upon low-energy photons (e.g., 360 nm) excitation. The dual-band emission with an additional blue emission band upon high-energy photons (e.g., 300 nm) excitation enable (TTA) 2 SbCl 5 to be a single-component phosphor for white light emission with a PLQE of 68%, correlated color temperature (CCT) of 2360 K and color rendering index (CRI) of 84. Based on photoluminescence spectra measurements and density functional theory calculations, the dual-band emission is assigned to the radiative recombination from both singlet and triplet self-trapped excitons in inorganic [SbCl 5 ] 2− pyramids. In addition, both luminescent compounds exhibit excellent stability against humidity and thermal attacks. Using (TEBA) 2 SbCl 5 as a yellow downconversion material, highly stable white-light-emitting diodes with a Commission Internationale de l'Eclairage (CIE) of (0.36, 0.33), CCT of 4282 K, and CRI of 82 were demonstrated. These results validate that the title 0D lead-free OIMHs with a dual-band emission and a near-unity PLQE are promising luminescent materials for solid-state lighting.

Efficient Lone-Pair-Driven Luminescence: Structure–Property Relationships in Emissive 5s2 Metal Halides

“…(C) Excitation-dependent PL of (bmpip) 2 SnBr 4 showing singlet and triplet emission. 34 (D) PL and PL excitation (PLE) spectra of (TTA) 2 SbCl 5 showing the separate excitation of the triplet and singlet states (reproduced using the previously reported synthesis 38 and characterized using an optical setup described elsewhere 34 ). (E) PL and PLE spectra of Cs 4 SnBr 6 , 37 (C 4 N 2 H 14 Br) 4 SnBr 6 , 19 and [18-crown-6] 2 Cs 3 SbBr 6 .…”

“… 19 , 119 One such compound is TTA 2 SbCl 5 , which further demonstrates the excitation-wavelength-dependent nature of the emission ( Figure 4 D). 38 High-energy excitation succeeds in populating the high-energy singlet 1 P 1 state, resulting in emission directly from this state as well as emission from the thermodynamically favored lower-energy 3 P 1 triplet state.…”

Supramolecular Approach for Fine-Tuning of the Bright Luminescence from Zero-Dimensional Antimony(III) Halides

“… 8 A similar study has also been conducted on (Et 4 N) 2 SbCl 5 proving that the model is valid in case of Sb. 29 Seitz model can also be extended with molecular orbital theory to account for the ligand field influence. 46 Upon hybridization with molecular orbitals of the ligands, resulting molecular states are derived from respective atomic states ( 3 P 0 , 3 P 1 , 3 P 2 , and 1 P 1 ) and preserve multiplicity (singlet or triplet).…”

“…In agreement, SbCl 5 compounds typically exhibit one additional emission band in the blue region, unlike SbCl 6 3– . 29 , 39 Typically for an STE, a large structural change occurs once electron is promoted to LUMO. This structural change has been previously accessed with DFT for various 0D Sn and Sb emitters.…”

Rare Earth‐Free Luminescent Materials for WLEDs: Recent Progress and Perspectives

“…Both lead‐free hybrid perovskite materials exhibited a high PLQY (86% and 98%), and the (TEBA) 2 SbCl 5 perovskite emitted warm white light with CIE coordinates (0.48, 0.46) under 300 nm excitation. [ 99 ] In order to study the origin of white light emission in SbCl 5 2− compounds, Xu et al designed and synthesized a series of organic–inorganic hybrid Sb‐based perovskites, and achieved a PLQY of 54%. [ 100 ] For Mn‐doped tin‐based hybrid perovskite materials such as (C 8 H 17 NH 2 ) 2 Sn 0.74 Mn 0.26 Br 4 , increasing Mn doping concentrations red‐shifted the emission spectrum and increased the half‐width.…”