Local Structure Distortion Induced Broad Band Emission in the All-Inorganic BaScO₂F:Eu²⁺ Perovskite

Abstract

Perovskites are a class of materials with applications in photovoltaics, solid-state lighting, and catalysis. Extensive research has gone into modifying the chemical composition of these distortion-prone structures to manipulate and achieve their tremendous physical properties. Here, we report a BaScO2F perovskite that, when doped with Eu2+, produces a highly efficient cyan emission stemming from the structure’s high symmetry and dense connectivity. However, the emission peak is broader than expected and steady-state, temperature-dependent, and time-resolved photoluminescence spectroscopy reveals the presence of two distinct emission peaks despite a single rare-earth substitution site. Ab initio calculations subsequently prove that substituting the smaller Eu2+ induces an unexpected local structure distortion driven by zone-boundary octahedral tilting. This produces two different local coordination environments around Eu2+ that cause the dual emission. This work shows the critical need to analyze local distortions in phosphors upon rare-earth substitution, especially in perovskites on the verge of structural instabilities.

Ca[B8O11(OH)4] : Eu2+ – A Highly Efficient Deep Blue‐Emitting Phosphor Prepared by Low‐Temperature Self‐reduction

“…The slope of the linear equation is Ea , whose value is 0.33 eV, as shown in Figure 7c. Compared with other Eu 2+ doped blue phosphors, the Ea of CBH : Eu 2+ is higher than those of Ba 3 Si 6 O 12 N 2 : Eu 2+ ( Ea =0.24 eV), [72] RbNa(Li 3 SiO 4 ) 2 : Eu 2+ ( Ea= 0.25 eV), [73] K 2 YZr(PO 4 ) 3 : Eu 2+ ( Ea= 0.25 eV), [68] Ba 3 CaK(PO 4 ) 3 : Eu 2+ ( Ea= 0.26 eV ), [70] K 2 Al 2 B 2 O 7 : Eu 2+ ( Ea =0.30 eV) [74] . But the Ea of CBH : Eu 2+ is lower than that of Sr 5 SiO 4 Cl 6 : Eu 2+ ( Ea =0.35 eV), [75] K 2 BaCa(PO 4 ) 2 : Eu 2+ ( Ea =0.51 eV), [76] and KBa 2 (PO 3 ) 5 : Eu 2+ ( Ea= 0.66 eV) [77] .…”

Giant Red‐Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near‐Infrared Luminescence

“…The higher activation energy (ΔE) contributes to better thermal stability. The ΔE of SrY 2 O 4 :0.06Eu 2+ and Sr 0.5 Ba 0.5 Y 2 O 4 :0.06Eu 2+ can be determined by the Arrhenius formula as follows: [24]…”

“…Figure 6e shows PL decay curves of SrY 2 O 4 :0.06Eu 2+ and Sr 0.5 Ba 0.5 Y 2 O 4 :0.06Eu 2+ at RT under 450 nm pulse laser diode excitation. The decay curves are fitted using a doubleexponential decay model function to obtain the τ av according to function: [24,27]…”

Local environment rigidity and the evolution of optical properties in the green-emitting phosphor Ba1−xSrxScO2F:Eu2+

“…Upon UV excitation, the product produces a broad emission (l em = 481 nm, fwhm = 103 nm). 20 The full width at half maximum and position of the emission band makes this phosphor ideal for covering the cyan gap. In addition, this phosphor possesses a high PLQY (80%) stemming from the dense connectivity of the perovskite crystal structure.…”

“…In addition, this phosphor possesses a high PLQY (80%) stemming from the dense connectivity of the perovskite crystal structure. Indeed, the rigid framework of corner-connected [Sc(O/F) 6 ] octahedra gives rise to a high Debye temperature of 517 K. 20 Unfortunately, this phosphor is not yet suitable for device integration due to its insufficient thermal stability. BaScO 2 F:Eu 2+ loses 50% of its low temperature (80 K) integrated emission intensity at 387 K, which is below the US.…”