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Broadband emissive perovskites are next‐generation materials for solid‐state lighting and radiative detection. However, white‐emitting perovskites are generally synthesized by regulating B/X sites, while not enough attention is paid to the A‐site, which is thought to hardly affect the band‐edge structures and optoelectronic properties. Here, a series of Sb3+‐doped In‐based 0D halide perovskite derivatives are described with various organoammonium cations in A‐sites. Warm‐white light emitting across the visible spectrum (450–850 nm), large Stokes shifts, and high photoluminescence quantum yields are easily tunable by molecularly tailoring A‐site cations. These features enable a light yield up to 60976 Photons/MeV as X‐ray scintillator, and a detection limit of 90 nGyair/s that is ≈60 times lower than the medical requirement. It is proved that A‐site plays a critical role in determining the degree of distortion of polyhedra, which influences the broadband photoluminescence and self‐trapped exciton (STE) dominates the emission process. Moreover, for the first time, via the incorporation of 2,6‐dimethylpiperazine, a mixed A‐site regulating strategy produces a standard white‐light emission, which originates from the blue‐light and yellow‐light related to various STE emission centers. It is foreseen that this strategy highlights the expanded role of A‐site and the importance of rethinking A‐sites in perovskites. [ABSTRACT FROM AUTHOR]

The development of metal‐halide perovskite nanocrystals (NCs) that yield bright and stable emission is of great importance. Previous reported perovskite NCs are mostly based on APbX3‐type family fabricated via ligand‐ or surfactant‐assisted chemical approaches. However, realizing bright and stable emission remains a challenge because of desorption of ligands/surfactants during long‐term operation. Herein, Ruddlesden–Popper (RP)‐type (A)2(MA)n‐1PbnBr3n+1 NCs with size less than Bohr radius stabilized in mesoporous silica scaffold, which are prepared in situ via physical approach at low temperature are introduced. The RP NCs in mesoporous silica exhibit the formation of spatially and electronically separated quantum wells, efficient energy funneling between different n phases for bright emission (photoluminescence quantum yields of ≈99%), high irradiation stability (T70 = 110 days), and long‐term stability (T90 = 110 days). These RP NCs have broad potential for bright light‐emitting diodes, high‐resolution PL imaging, and waterproof inks. Importantly, for the first time, stretchable perovskite X‐ray scintillator is demonstrated with excellent X‐ray imaging with resolution greater than 14 line pairs mm−1. These findings offer a paradigm to motivate future research toward stable and efficient perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

The development of metal‐halide perovskite nanocrystals (NCs) that yield bright and stable emission is of great importance. Previous reported perovskite NCs are mostly based on APbX3‐type family fabricated via ligand‐ or surfactant‐assisted chemical approaches. However, realizing bright and stable emission remains a challenge because of desorption of ligands/surfactants during long‐term operation. Herein, Ruddlesden–Popper (RP)‐type (A)2(MA)n‐1PbnBr3n+1 NCs with size less than Bohr radius stabilized in mesoporous silica scaffold, which are prepared in situ via physical approach at low temperature are introduced. The RP NCs in mesoporous silica exhibit the formation of spatially and electronically separated quantum wells, efficient energy funneling between different n phases for bright emission (photoluminescence quantum yields of ≈99%), high irradiation stability (T70 = 110 days), and long‐term stability (T90 = 110 days). These RP NCs have broad potential for bright light‐emitting diodes, high‐resolution PL imaging, and waterproof inks. Importantly, for the first time, stretchable perovskite X‐ray scintillator is demonstrated with excellent X‐ray imaging with resolution greater than 14 line pairs mm−1. These findings offer a paradigm to motivate future research toward stable and efficient perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

Both semiconductors and scintillators have their own advantages in direct and indirect X‐ray detection, respectively. However, they are also limited by their intrinsic properties and detection mechanisms. Here, a low‐cost and large‐area flat X‐ray detector is reported by combining a cesium silver bismuth bromide (Cs2AgBiBr6) perovskite semiconductor with a ethylenebis‐triphenylphosphonium manganese (II) bromide ((C38H34P2)MnBr4) scintillator through fast tableting processes. Cs2AgBiBr6 and (C38H34P2)MnBr4 can attenuate the X‐ray photons to induce charge carriers that are collected through the continuous Cs2AgBiBr6 grains. (C38H34P2)MnBr4 blocks the Cs2AgBiBr6 ions migration paths at the grain boundaries to reduce the device dark current/noise and improves the working stability. Most charges generated by (C38H34P2)MnBr4 are transferred to the adjacent Cs2AgBiBr6, and recombined charges radiate light through scintillation, which will be further absorbed by the surrounding Cs2AgBiBr6 perovskite, and further induce collectable charges for indirect X‐ray detection, avoiding the unwanted light scattering, self‐absorption, or afterglow effects of scintillators. The hybrid X‐ray detector displays a high sensitivity of 114 µC Gyair−1 cm−2 to 120 keVp hard X‐rays with a lowest detectable dose rate of 0.2 μGyair s−1, showing 75 times lower detection limit compared to (C38H34P2)MnBr4 scintillator, which provides a new path for X‐ray flat‐panel design. [ABSTRACT FROM AUTHOR]

Environmental friendly metal halides have become emerging candidates as energy downconverting emitters for lighting and X‐ray imaging applications. Herein, luminescent single crystals of tetramethylammonium manganese chloride (C4H12NMnCl3) and tetraethylammonium bromide ((C8H20N)2MnBr4) are synthesized via a facile room‐temperature evaporation method. C4H12NMnCl3 and (C8H20N)2MnBr4 with octahedrally and tetrahedrally coordinated Mn2+ have correspondingly exhibited red and green emission peaking at 635 and 515 nm both originating from 4T1–6A1 transition of Mn2+ with high photoluminescence quantum yield (PLQY) of 91.8% and 85.1% benefiting from their specific crystal structures. Thanks to their strong photoexcitation under blue light, high PLQY, tunable emission spectra, good environmental stability, the white light‐emitting diode based on blending of C4H12NMnCl3 and (C8H20N)2MnBr4 delivers an outstanding luminous efficacy of 96 lm W−1, approaching commercial level, and shows no obvious photoluminescence intensity degradation after 3000 h under operation. In addition, manganese halides also demonstrate interesting characteristics under X‐ray excitation, C4H12NMnCl3 and (C8H20N)2MnBr4 exhibit steady‐state X‐ray light yields of 50 500 and 24 400 photons MeV−1, low detectable limits of 36.9 and 24.2 nGyair s−1, good radiation hardness, and X‐ray imaging demonstration with high‐resolution of 5 lp mm−1. This work presents a new avenue for luminescent Mn‐based metal halides toward multifunctional light‐emitting applications. [ABSTRACT FROM AUTHOR]

Thrombosis is a frequent predisposing factor in high‐mortality cardiovascular diseases, which underscores the urgent need to precisely diagnose thrombosis formation at a less severe stage. However, it is still challenging to realize in vivo early thrombosis imaging due to lack of high sensitivity/‐specificity molecular imaging strategy. To address such problems, thrombin‐activatable scintillating nanoprobes are developed for background‐free X‐ray‐excited luminescence (XEL) imaging of in vivo early thrombosis. The nanoprobes are constructed by designing bright XEL‐emitting lanthanide‐doped scintillator nanocrystals (NCs) with dye labeled‐peptide modification. Such nanoprobes show XEL‐off originally and enable robust turn‐on XEL upon thrombin‐specific cleavage of the peptide, resulting from the rational manipulation of energy transfer between dye and NCs. Specially, due to high tissue penetration depth and background‐free attributes in XEL imaging, this strategy achieves high‐efficiency XEL imaging of the early thrombosis on the basis of in situ elevated thrombin levels. Moreover, XEL and magnetic resonance imaging capabilities can be integrated to further improve imaging accuracy and monitor thrombosis progression. As such, the exploited strategy demonstrates a novel paradigm for realizing timely thrombosis imaging and provides a new readily tailorable platform for sensitive in vivo deep‐tissue imaging. [ABSTRACT FROM AUTHOR]