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Scintillators, one of the essential components in medical imaging and security checking devices, rely heavily on rare‐earth‐containing inorganic materials. Here, a new type of organic‐inorganic hybrid scintillators containing earth abundant elements that can be prepared via low‐temperature processes is reported. With room temperature co‐crystallization of an aggregation‐induced emission (AIE) organic halide, 4‐(4‐(diphenylamino) phenyl)‐1‐(propyl)‐pyrindin‐1ium bromide (TPA‐PBr), and a metal halide, zinc bromide (ZnBr₂), a zero‐dimensional (0D) organic metal halide hybrid (TPA‐P)₂ZnBr₄with a yellowish‐green emission peaked at 550 nm has been developed. In this hybrid material, dramatically enhanced X‐ray scintillation of TPA‐P⁺is achieved via the sensitization by ZnBr₄²⁻. The absolute light yield (14,700 ± 800 Photons/MeV) of (TPA‐P)₂ZnBr₄is found to be higher than that of anthracene (≈13,500 Photons/MeV), a well‐known organic scintillator, while its X‐ray absorption is comparable to those of inorganic scintillators. With TPA‐P⁺as an emitting center, short photoluminescence and radioluminescence decay lifetimes of 3.56 and 9.96 ns have been achieved. Taking the advantages of high X‐ray absorption of metal halides and efficient radioluminescence with short decay lifetimes of organic cations, the material design paves a new pathway to address the issues of low X‐ray absorption of organic scintillators and long decay lifetimes of inorganic scintillators simultaneously.

Zero‐dimensional (0D) organic metal halide hybrids (OMHHs) have recently emerged as a new class of light emitting materials with exceptional color tunability. While near‐unity photoluminescence quantum efficiencies (PLQEs) are routinely obtained for a large number of 0D OMHHs, it remains challenging to apply them as emitter for electrically driven light emitting diodes (LEDs), largely due to the low conductivity of wide bandgap organic cations. Here, the development of a new OMHH, triphenyl(9‐phenyl‐9H‐carbazol‐3‐yl) phosphonium antimony bromide (TPPcarzSbBr₄), as emitter for efficient LEDs, which consists of semiconducting organic cations (TPPcarz⁺) and light emitting antimony bromide anions (Sb₂Br₈²⁻), is reported. By replacing one of the phenyl groups in a well‐known tetraphenylphosphonium cation (TPP⁺) with an electroactive phenylcarbazole group, a semiconducting TPPcarz⁺cation is developed for the preparation of red emitting 0D TPPcarzSbBr₄single crystals with a high PLQE of 93.8%. With solution processed TPPcarzSbBr₄thin films (PLQE of 86.1%) as light emitting layer, red LEDs are fabricated to exhibit an external quantum efficiency (EQE) of 5.12%, a peak luminance of 5957 cd m⁻², and a current efficiency of 14.2 cd A⁻¹, which are the best values reported to date for electroluminescence devices based on 0D OMHHs.

Metal halide perovskite nanocrystals (NCs) have emerged as highly promising light emitting materials for various applications, ranging from perovskite light‐emitting diodes (PeLEDs) to lasers and radiation detectors. While remarkable progress has been achieved in highly efficient and stable green, red, and infrared perovskite NCs, obtaining efficient and stable blue‐emitting perovskite NCs remains a great challenge. Here, a facile synthetic approach for the preparation of blue emitting CsPbBr₃nanoplatelets (NPLs) with treatment by an organic sulfate is reported, 2,2‐(ethylenedioxy) bis(ethylammonium) sulfate (EDBESO₄), which exhibit remarkably enhanced photoluminescence quantum efficiency (PLQE) and stability as compared to pristine CsPbBr₃NPLs coated with oleylamines. The PLQE is improved from ≈28% for pristine CsPbBr₃NPLs to 85% for EDBESO₄treated CsPbBr₃NPLs. Detailed structural characterizations reveal that EDBESO₄treatment leads to surface passivation of CsPbBr₃NPLs by both EDBE²⁺and SO₄^2–ions, which helps to prevent the coalescence of NPLs and suppress the degradation of NPLs. A simple proof‐of‐concept device with emission peaked at 462 nm exhibits an external quantum efficiency of 1.77% with a luminance of 691 cd m⁻²and a half‐lifetime of 20 min, which represents one of the brightest pure blue PeLEDs based on NPLs reported to date.