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

Low-dimensional organic-inorganic metal halide hybrids (OIMHs) with an ultrabroad-band emission are promising as down conversion phosphors for solid-state lighting. However, toxicity of Pb and low photoluminescence quantum efficiency (PLQE) hamper their application. Herein, two zero-dimensional (OD) lead-free organic antimony (Sb) chloride (Cl) hybrids with dual-band emissions and PLQEs: (TTA)(2)SbCl5 (TTA = tetraethylammonium) and (TEBA)(2)SbCl5 (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)SbCl5 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 [SbCl5](2-) pyramids. In addition, both luminescent compounds exhibit excellent stability against humidity and thermal attacks. Using (TEBA)(2)SbCl5 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 OD lead-free OIMHs with a dual-band emission and a near-unity PLQE are promising luminescent materials for solid-state lighting.