Flexible scintillator screens with environmental stability, high sensitivity, and low cost have emerged as candidates for X‐ray imaging applications. Here, a large‐scale and cost‐efficient solution synthesis of the vacancy‐ordered double perovskite Cs2ZrCl6, which is characterized by thermal activation delayed fluorescence (TADF) dominated by triplet emission under X‐ray irradiation, is demonstrated. The large Stokes shift and efficient luminescence collection of TADF effectively ensure the light outcoupling efficiency. Further, flexible X‐ray scintillator screens with an area of 400 cm2 are prepared using poly(dimethylsiloxane) (PDMS) as the carrier, exhibiting excellent scintillation properties with light yields as high as 49 400 photons MeV−1, spatial resolutions up to 18 lp mm−1 and detection limits as low as 65 nGy s−1. Finally, the high‐quality imaging results of non‐planar and dynamic objects by such screens are demonstrated. It is believed that the explored Cs2ZrCl6@PDMS flexible scintillator screens would offer a big step toward expanding the application range of scintillators in different environments.

This work unifies the metrics of lanthanide-based LIR nanothermometers, rectifies previous misunderstanding of Sa, and provides detailed guidance.

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The rapid development of solid-state lighting technology has attracted much attention for searching efficient and stable luminescent materials, especially the single-component white-light emitter. Here, we adopt a facile ion-doping technology to synthesize vacancy-ordered double perovskite Cs 2 ZrCl 6 :Sb. The introduction of Sb 3+ ions with a 5s 2 active lone pair into Cs 2 ZrCl 6 host stimulates the singlet (blue) and triplet (orange) states emission of Sb 3+ ions, and their relative emission intensity can be tuned through the energy transfer from singlet to triplet states. Benefiting from the dual-band emission as a pair of perfect complementary colors, the optimum Cs 2 ZrCl 6 :1.5%Sb exhibits a high-quality white emission with a colorrendering index of 96. By employing Cs 2 ZrCl 6 :1.5%Sb as the downconversion phosphor, stable single-component white light-emitting diodes with a record half-lifetime of 2003 h were further fabricated. This study puts forward an effective ion-doping strategy to design single-component white-light emitter, making practical applications of them in lighting technologies a real possibility.

Luminescence nanothermometers are promising for noninvasive, high resolution thermographics ranging from aeronautics to biomedicine. Yet, limited success has been met in the NIR‐II/III biological windows, which allow temperature evaluation in deep tissues. Herein, a new type of phonon‐based ratiometric thermometry is described that utilizes the luminescence intensity ratio (LIR) between holmium (Ho3+) emission at ≈1190 nm (NIR‐II) and erbium (Er3+) emission at ≈1550 nm (NIR‐III) from a set of oxide nanoparticles of varying host lattices. It is shown that multi‐phonon relaxation in Er3+ ions and phonon‐assisted transfer process in Ho3+ ions play a significant role in LIR determination through channeling the harvested excitation energy to the corresponding emitting states. As a result, temperature sensitivity can be tuned by the dominant phonon energy of host lattice, thus endowing aqueous yttrium oxide (Y2O3, 376 cm−1) nanoparticles to have a relative temperature sensitivity of 1.01% K−1 and absolute temperature sensitivity of 0.0127 K−1 at 65 °C in a physiological temperature range (25–65 °C). And their temperature sensing for biological tissues is further explored and the influence of water and chicken breast on thermometry is discussed. This work constitutes a solid step forward to build sensitive NIR‐II/III nanothermometers for biological applications.