All Inorganic Sb³⁺–Ln³⁺‐Codoped Cs₂NaYCl₆ for Highly Efficient Single‐Source White‐Light Emission and Ratiometric Optical Thermometer Applications

Abstract

Single‐source white‐light emitters are highlighted with stable color and excellent color rendering ability, which can largely simplify the white‐light‐emitting‐diode (WLED) structure. All‐inorganic and lead‐free double perovskites have attracted extensive research interest and provide versatile doping sites to accommodate the extrinsic multi‐valent ions. Herein, the synthesis and tunable emission of Sb3+–Ln3+‐codoped Cs2NaYCl6 single crystals (SCs) is reported. Particularly, bright white‐light emission with a high photoluminescence quantum yield of 80.5% is yielded in 0.5%Sb3+–2%Tb3+–2%Sm3+‐codoped Cs2NaYCl6 SCs. Steady‐state photoluminescence (PL) and time‐resolved PL spectra are employed to reveal the energy transfer from Sb3+‐induced self‐trapped excitons to Ln3+ ions. Temperature‐dependent PL spectra further demonstrate that the fluorescence intensity ratio of band 657 to band 590 nm is highly dependent on the temperature, and the relative sensitivity reaches a maximum of up to 1.59% K−1 at 260 K. Moreover, the WLED based on 0.5%Sb3+‐2%Tb3+‐2%Sm3+‐codoped Cs2NaYCl6 SCs delivers a higher average color rendering index of 87 than 0.5%Sb3+‐0.8%Tb3+‐2.5%Ho3+‐codoped Cs2NaYCl6 (74.6). The outstanding white‐light‐emission performance together with the high temperature dependence of the fluorescence spectra confers Sb3+–Ln3+‐codoped Cs2NaYCl6 with huge application potential in solid‐state lighting and ratiometric optical thermometry.

Near‐infrared emitting metal halide materials: Luminescence design and applications

“…39,51 In addition to the above two types of emission, ion emission accounts for a large portion in LMHs, originating from d-d transitions of transition metal ions (e.g., Mn 2+ and Cr 3+ ), f-f transitions of trivalent lanthanide ions (e.g., Sm 3+ , Yb 3+ and Er 3+ ), f-d transitions of divalent lanthanide ions (e.g., Eu 2+ and Sm 2+ ), as well as s-p/p-p transitions of bismuth ions, and so forth. [52][53][54][55][56] Tunable luminescence properties of the ion emission can be achieved by adjusting the lattice environment. Moreover, energy transfer can be designed to improve the luminescence efficiency.…”

Achieving high-sensitivity dual-mode optical thermometry via phonon-assisted cross-relaxation in a double-perovskite structured up-conversion phosphor

“…1–3 Among them, FIR-based thermometry has become a widely used temperature measurement technology solution due to its advantages such as fast response speed and a wide temperature measurement range. 4–6 FIR technology can be implemented in two ways: thermal coupling level (TCL) and non-thermal coupling level (NTCL). 7,8 However, since the energy gap (Δ E ) of the TCL is limited to a range of 200–2000 cm −1 , it is difficult to obtain high relative sensitivity because it is proportional to Δ E ( S r = Δ E / kT 2 ).…”