efficiency,low-energy consumption, long lifetime, and environmental compatibility, and so on. [1][2][3] The common w-LEDs devices are fabricated via two combination strategies: 1) blue LED chip and yellow phosphor; 2) nearultraviolet (n-UV) LED chip and tricolor phosphors. [4,5] No matter for which fabrication methods, the development of red phosphor is crucial to improve the lighting quality and tune corrected color temperature of w-LEDs. [6,7] To date, many researchers have focused on exploring highly efficient red phosphors. Although Eu 2+ -doped nitride phosphors such as CaAlSiN 3 :Eu 2+ and Sr 2 Si 5 N 8 :Eu 2+[8-10] show high quantum yield (QY > 90%) and high thermal quenching temperature (>600 K), the harsh preparation conditions (high pressure ≥ 0.9-2.5 MPa; high temperature ≥1700-200 °C) and deepred emission position (beyond 650 nm) limit the large-scale application in indoor lighting. Eu 3+ -doped inorganic compounds are typical red-emitting phosphors due to the (4f 6 ) 5 D 0 → (4f 6 ) 7 F J spin-and parity-forbidden transition, [11,12] but it is hardly utilized in w-LEDs applications owing to the linearly narrow excitation and emission. [13,14] Mn 4+ has been considered as the promising red-emitting activator Nowadays, red phosphor plays a key role in improving the lighting quality and color rendering index of phosphor-converted white light emitting diodes (w-LEDs). However, the development of thermally stable and highly efficient red phosphor is still a pivotal challenge. Herein, a new strategy to design antithermal-quenching red emission in Eu 3+ , Mn 4+ -codoped phosphors is proposed.

Near-infrared light-emitting diodes (NIR-LEDs) are potential candidates in food composition analysis, temperature and security monitoring, biometrics, and medical applications. To realize the above objectives, the development of NIR-emitting phosphors is urgently required. Herein, a novel NIR emission is successfully achieved in Bi3+-activated XAl12O19 (X = Ba, Sr, Ca) compounds by constructing the selective site occupation of Bi3+ in Al3+ polyhedra with small coordination number. The designed phosphors exhibit broad-band NIR emission of Bi3+ from 600 to 1000 nm. Interestingly, a broad photoluminescence control from blue to red is also achieved by just changing the sintering atmosphere. The blue emission of Bi3+ should be assigned to the prior occupation in X2+ sites and the existence of oxygen vacancy. This work not only provides a novel insight to develop NIR-emitting Bi3+-activated phosphors but also helps to reveal the underlying NIR luminescence mechanism of Bi3+ in inorganic compounds.

A highly stable and efficient CsPbBr3@SiO2 composite phosphor is achieved by protecting the CsPbBr3 QDs from direct exposure to the atmosphere by encapsulating CsPbBr3 into dual-shell hollow silica nanospheres.

As increasing demand for noncontact temperature sensing, the development of a high-performance optical thermometer probe is more and more urgent. In this work, an efficient dual-mode optical thermometry strategy based on the Pr 3+ /Dy 3+ energy transfer (ET) in some typical double-perovskite oxides is presented, which offers a promising way to design FIR/lifetime dual-mode optical thermometry with excellent temperature-measuring sensitivity and signal discrimination. According to this strategy, double-perovskite La 2 MgTiO 6 :Pr 3+ /Dy 3+ phosphors are successfully synthesized. On the basis of diverse thermal responses between Pr 3+ and Dy 3+ , the FIR of Pr 3+ to Dy 3+ (four FIR mode) in this material displays outstanding optical thermometry performance from 298 to 548 K. The maximum absolute and relative sensitivities (S a and S r ) of mode 1 are 0.09 and 2.357% K −1 , being better than the current optical temperature measurement materials. For the fluorescence lifetime mode, the S a-max and S r-max values reach 2.85 × s 10 −4 and 1.814% K −1 . Furthermore, the dual-mode optical thermometry mechanism was presented and studied. It also demonstrated excellent optical thermometry performance in the other Pr 3+ /Dy 3+ codoped double-perovskite oxides, such as LaMg 0.598 Nb 0.402 O 3 , NaLa(MoO 4 ) 2 , NaGd(MoO 4 ) 2 , and NaLa(WO 4 ) 2 , proving the universality of the presented strategy. This article presents an effective Pr 3+ /Dy 3+ ET pathway for developing new and highly sensitive FIR/lifetime dual-mode optical temperature sensing materials.

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