The relatively low resistivity and severe ion migration in inorganic perovskite CsPbBr3 significantly degrade the performance of X-ray detectors due to their high detection limit and current drift. We investigate the electrical properties and X-ray detection performances of CsPbBr3-n In single crystals by doping the iodine atoms into the melt-grown CsPbBr3 crystals. The resistivity of CsPbBr3-n In single crystals increases from 3.6 × 109 (CsPbBr3 ) to 2.2 × 1011 (CsPbBr2 I) Ω·cm as the iodine content increases, restraining the leak current and decreasing the detection limit of the detector. Additionally, CsPbBr3-n In single crystals exhibit stable dark currents under an electric field of 5000 V cm-1 , arising from their high ion migration activation energy. A record sensitivity of 6.3 × 104 μC Gy-1  cm-2 (CsPbBr2.9 I0.1 ) and a low detection limit of 54 nGy s-1 (CsPbBr2 I) are achieved by CsPbBr3-n In single crystals for the 120 keV hard X-ray detection under a 5000 V cm-1 electrical field. The CsPbBr2.9 I0.1 detector shows a stable current response with a dark current density of 0.58 μA cm-2 for 30 days and clear imaging for 120 keV X-rays at ambient conditions. The effective iodine atom doping strategy and the high quality make the CsPbBr3-n In SCs single crystals promising for reproducible high-energy hard X-ray imaging systems. This article is protected by copyright. All rights reserved.

Ultrasensitive and Robust 120 keV Hard X-ray Imaging Detector Based on Mixed-Halide Perovskite CsPbBr3-n In Single Crystals.

Halide perovskites are promising candidates for soft X-ray detection (<80 keV) owing to their high X-ray absorption coefficient, resistivity, and mobility lifetime product. However, the lack of large high-quality single crystals (SCs) renders it challenging to manufacture robust hard X-ray imaging systems (>100 keV) with a low detection limit and stable dark current. Herein, high-quality inch-size two-dimensional (2D) Cs3Bi2Br9 (CBB) single crystals are grown from a melt via the Bridgman method. The crystal quality is enhanced by eliminating inclusions of CsBr-rich phases and restraining the trap-state density, leading to an enhanced resistivity of 1.41 × 1012 Ω cm and a mobility lifetime product of 8.32 × 10-4 cm2 V-1. The Au/CBB/Au single-crystal device exhibits a high sensitivity of 1705 μC Gyair-1 cm-2 in all-inorganic bismuth-based perovskites and an ultralow detection limit of 0.58 nGyair s-1 in all of the bismuth-based perovskites for 120 keV hard X-ray detection. The CBB detector exhibits high work stability with an ultralow dark current drift of 2.8 × 10-10 nA cm-1 s-1 V-1 and long-term air environment reliability under a high electric field of 10 000 V cm-1 owing to the ultrahigh ionic activation energy of the 2D structure. The proposed robust imaging system based on CBB SC is a promising tool for X-ray medical imaging and diagnostics.

Ultralow Detection Limit and Robust Hard X-ray Imaging Detector Based on Inch-Sized Lead-Free Perovskite Cs3Bi2Br9 Single Crystals.

Metal halide perovskite nanostructures have sparked intense research interest due to their excellent optical properties. In recent years, although the green and red perovskite light-emitting diodes (PeLEDs) have achieved a significant breakthrough with the external quantum efficiency exceeding 20%, the blue PeLEDs still suffer from inferior performance. Previous reviews about blue PeLEDs focus more on 2D/quasi-2D or 3D perovskite materials. To develop more stable and efficient blue PeLEDs, a systematic review of blue perovskite quantum dots (PQDs) is urgently demanded to clarify how PQDs evolve. In this review, the recent advances in blue PQDs involving mixed-halide, quantum-confined all-bromide, metal-doped and lead-free PQDs as well as their applications in PeLEDs are highlighted. Although several excellent PeLEDs based on these PQDs have been demonstrated, there are still many problems to be solved. A deep insight into the advantages and disadvantages of these four types of blue-emitting PQDs is provided. Then, their respective potential and issues for blue PeLEDs have been discussed. Finally, the challenges and outlook for efficient and stable blue PeLEDs based on PQDs are addressed.

Recent Advances in Blue Perovskite Quantum Dots for Light-Emitting Diodes

Metal clusters with color‐tunable radioluminescence have attracted growing attention as X‐ray detection materials. However, they are generally less scintillation‐efficient due to the coexistence of multiple exciton recombination centers. Herein, two new zero‐dimensional copper(I)‐based clusters (DIET)3Cu3X3 (DIET = 1,3‐Diethyl‐2‐thiourea, X = Cl, Br) are designed, which support the single channel photon emission (Cu cluster centered, CC) to enhance the scintillation performance. Those DIET ligands (L) anchoring with copper(I) ions not only generate direct CuL bonds, but also form a disorder [Cu3X3] cluster, which results in the intense X‐ray absorption. (DIET)3Cu3Br3 with low halogen electronegativity further weakens halogen‐to‐ligand charge transfer (XLCT) emission, enabling enhanced quantum efficiency (≈69%) and scintillation performance comparable to commercially available Lu3Al5O12:Ce. Moreover, the flexible thin film counterpart demonstrates legible X‐ray imaging with high spatial resolution of 11.71 lp mm−1. This study provides a feasible design principle to discover new metal cluster‐based scintillators and to further expand their radiation detection applications.

Promoting Single Channel Photon Emission in Copper(I) Halide Clusters for X‐Ray Detection

Self-Healing Cs3Bi2Br3I6 Perovskite Wafers for X-Ray Detection

All-inorganic lead-free halide perovskites have attracted interest owing to their high ambient and thermal stabilities, excellent optoelectronic properties, and environmental friendliness. Herein, the bismuth-based halide perovskite Cs3Bi2Br9 single crystals were successfully grown to a diameter of 12 mm and length of 40 mm using a modified Bridgman method for the first time. The resistivity and transmittance of transparent and crack-free Cs3Bi2Br9 single crystal are ~6.8×1011 Ω cm and ~80%, respectively. The carrier mobility of the (−120) plane is 0.17 cm2 V−1 s−1 along the [010] orientation (b axis), and the trap density is 9.7×1010 cm−3. Moreover, Cs3Bi2Br9 single crystals exhibit excellent potential for X-ray detection, including a high absorption coefficient, a superior X-ray sensitivity of ~230.4 µC Gyair−1 cm−2, and an ultra-low and no-drift dark current density of ~17.8 pA mm−2, which enables lower noise and is also beneficial to the ultra-low detection limit for X-ray detectors. Our study shows that Cs3Bi2Br9 is a promising candidate for X-ray detection applications.

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Lead-free halide perovskite Cs 3 Bi 2 Br 9 single crystals for high-performance X-ray detection

Narrowband photodetectors are critical for the application of sensors in imaging systems, spectroscopic photodetectors, and optical communication. All-inorganic mixed-halide perovskite (CsPbBr3−3nX3n, X = Cl, I) crystals have emerged as outstanding wavelength-selective light detection materials. They exhibit tunable optoelectronic properties and high stability, and can realize color discrimination without a filter or a bulk spectrometer. This study demonstrates the successful fabrication of a series of centimeter-sized mixed-halide perovskite (CsPbBr3−3nX3n) single crystals using the modified Bridgman method. The optical absorption edges of these crystals are continuously tuned from 437 to 664 nm, corresponding to the bandgaps of 2.88–1.90 eV, by changing the halide composition. Subsequently, eight filter-free narrowband photodetectors are fabricated based on the CsPbBr3−3nX3n bulk crystals. The narrowband photodetectors exhibit a widely tunable response range from violet to orange, a full-width at half-maximum of <20 nm, and an optimal responsivity of 0.59 A W−1, which demonstrates excellent spectral discrimination capabilities. Finally, a filter-free color image sensor, which is integrated with the CsPbBr3−3nX3n narrowband photodetectors, is constructed. The sensor exhibits excellent color and shape recognition abilities. These results demonstrate the exciting potential of the all-inorganic mixed-halide perovskite bulk crystals for the fabrication of compact, high-performance filter-free color image sensors.

Filter-free color image sensor based on CsPbBr3−3nX3n (X = Cl, I) single crystals

Origin of ultra-wide IR transmission and ultra-large birefringence of mercurous halide series with one dimensional chain-like structure: An ab initio study

Yunqiu Hua

Papers

Ultrasensitive and Robust 120 keV Hard X-ray Imaging Detector Based on Mixed-Halide Perovskite CsPbBr3-n In Single Crystals.

Lead-free halide perovskite Cs 3 Bi 2 Br 9 single crystals for high-performance X-ray detection

Ultralow Detection Limit and Robust Hard X-ray Imaging Detector Based on Inch-Sized Lead-Free Perovskite Cs3Bi2Br9 Single Crystals.

Filter-free color image sensor based on CsPbBr3−3nX3n (X = Cl, I) single crystals

Origin of ultra-wide IR transmission and ultra-large birefringence of mercurous halide series with one dimensional chain-like structure: An ab initio study