Commercialization of perovskite solar cells (PSCs) requires developing high-efficiency devices with good stability. Ionic defects existing in the perovskite layer can serve as nonradiative ...recombination centers to deteriorate the performance of PSCs and can introduce chemical degradation of the perovskite material introducing instability issues. Here, passivation molecules with various electron density distributions (EDD) are employed as an ideal model to reveal the role of EDD on defect passivation in perovskite thin films. Power conversion efficiency (PCE) exceeding 21% with good stability in humid air was obtained for planar PSCs with the 4-aminobenzonitrile (ABN) additive, higher than the reference PSCs with a PCE of 20.22%. The improved stability and performance features are attributed to the efficient passivation for charged defects in perovskites by adding ABN, which guarantees a smaller Urbach energy, longer carrier lifetime, and less traps in the perovskite films.
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X-ray detection has been widely used in medical imaging, security inspection, and industrial non-destructive tests. Halide perovskite X-ray detectors have attracted increasing attention due to their ...high sensitivity and low detection limit, but the notorious ion migration leads to poor operational stability. It is reported that the low dimensional structure can effectively suppress the ion migration of perovskites, thus greatly improving the stability of the detectors. This review introduces the working mechanism, key performance parameters of perovskite X-ray detectors, and summarizes the recent progress of lowdimensional perovskite materials and their application in direct X-ray detectors. The relationship between the structural characteristics of low-dimensional perovskite materials and their X-ray detection performance was systematically analyzed. Low-dimensional perovskite is a promising candidate for the preparation of X-ray detectors with both high sensitivity and stability. Further optimization of det
Abstract Quasi-two-dimensional (Q-2D) perovskite exhibits exceptional photoelectric properties and demonstrates reduced ion migration compared to 3D perovskite, making it a promising material for the ...fabrication of highly sensitive and stable X-ray detectors. However, achieving high-quality perovskite films with sufficient thickness for efficient X-ray absorption remains challenging. Herein, we present a novel approach to regulate the growth of Q-2D perovskite crystals in a mixed atmosphere comprising methylamine (CH 3 NH 2 , MA) and ammonia (NH 3 ), resulting in the successful fabrication of high-quality films with a thickness of hundreds of micrometers. Subsequently, we build a heterojunction X-ray detector by incorporating the perovskite layer with titanium dioxide (TiO 2 ). The precise regulation of perovskite crystal growth and the meticulous design of the device structure synergistically enhance the resistivity and carrier transport properties of the X-ray detector, resulting in an ultrahigh sensitivity (29721.4 μC Gy air −1 cm −2 ) for low-dimensional perovskite X-ray detectors and a low detection limit of 20.9 nGy air s −1 . We have further demonstrated a flat panel X-ray imager (FPXI) showing a high spatial resolution of 3.6 lp mm −1 and outstanding X-ray imaging capability under low X-ray doses. This work presents an effective methodology for achieving high-performance Q-2D perovskite FPXIs that holds great promise for various applications in imaging technology.
X‐ray detectors are widely utilized in medical diagnostics and nondestructive product inspection. Halide perovskites are recently demonstrated as excellent candidates for direct X‐ray detection. ...However, it is still challenging to obtain high quality perovskites with millimeter‐thick over a large area for high performance, stable X‐ray detectors. Here, methylammonium bismuth iodide (MA3Bi2I9) polycrystalline pellets (PPs) are developed by a robust, cost effective, and scalable cold isostatic‐pressing for fabricating X‐ray detectors with low limit of detection (LoD) and superior operational stability. The MA3Bi2I9‐PPs possess a high resistivity of 2.28 × 1011 Ω cm and low dark carrier concentration of ≈107 cm−3, and balanced mobility of ≈2 cm2 V−1 s−1 for electrons and holes. These merits enable a sensitivity of 563 μC Gyair−1 cm−2, a detection efficiency of 28.8%, and an LoD of 9.3 nGyair s−1 for MA3Bi2I9‐PPs detectors, and the LoD is much lower than the dose rate required for X‐ray diagnostics used currently (5.5 μGyair s−1). In addition, the MA3Bi2I9‐PPs detectors work stably under high working bias field up to 2000 V cm−1 after sensing an integrated dose >320 Gyair with continuous X‐ray radiation, demonstrating its competitive advantage in practical application. These findings provide an approach to explore a new generation of low LoD, stable and green X‐ray detectors based on MA3Bi2I9‐PPs.
MA3Bi2I9 polycrystalline pellets (PPs) are fabricated by the robust, cost‐effective, and scalable cold isostatic‐pressing approach, and X‐ray detectors based on MA3Bi2I9‐PPs reach a limit of detection (LoD) of 9.3 nGyair s−1. The low LoD of the X‐ray detectors can obviously decrease the radiation dose used, thereby reducing health risks in medical diagnostics and security screening.
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Sensitive and reliable X-ray detectors are essential for medical radiography, industrial inspection and security screening. Lowering the radiation dose allows reduced health risks and increased ...frequency and fidelity of diagnostic technologies for earlier detection of disease and its recurrence. Three-dimensional (3D) organic–inorganic hybrid lead halide perovskites are promising for direct X-ray detection – they show improved sensitivity compared to conventional X-ray detectors. However, their high and unstable dark current, caused by ion migration and high dark carrier concentration in the 3D hybrid perovskites, limits their performance and long-term operation stability. Here we report ultrasensitive, stable X-ray detectors made using zero-dimensional (0D) methylammonium bismuth iodide perovskite (MA3Bi2I9) single crystals. The 0D crystal structure leads to a high activation energy (Ea) for ion migration (0.46 eV) and is also accompanied by a low dark carrier concentration (~ 106 cm−3). The X-ray detectors exhibit sensitivity of 10,620 µC Gyair−1 cm−2, a limit of detection (LoD) of 0.62 nGyair s−1, and stable operation even under high applied biases; no deterioration in detection performance was observed following sensing of an integrated X-ray irradiation dose of ~23,800 mGyair, equivalent to > 200,000 times the dose required for a single commercial X-ray chest radiograph. Regulating the ion migration channels and decreasing the dark carrier concentration in perovskites provide routes for stable and ultrasensitive X-ray detectors.
A new kind solution-processed zero-dimensional lead-free perovskite is developed for ultrasensitive and stable X-ray detection. The advance presented herein provides a new route to accelerate the adoption of perovskites in X-ray imaging and medical applications. Display omitted
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Halide perovskites have attracted significant research interests in the X-ray detection and imaging field. Their strong X-ray attenuating ability and good carrier transportation endow them with high ...sensitivity, which is better than those of commercialized amorphous selenium (a-Se) and CdZnTe (CZT). However, ion migration has been identified as a critical factor that deteriorates the performance of three-dimensional (3D) lead-based halide perovskite detectors. Moreover, large dark current has hindered their application in low-dose X-ray detection. Another major challenge is to fabricate large area, high-quality thick perovskites that can be integrated with commercial electronic readout backplanes, such as thin-film transistors (TFTs) and complementary metal-oxide-semiconductor (CMOS) transistors, to produce multipixel flat-panel detectors for X-ray imaging. Bismuth-based halide perovskites have been demonstrated to be competitive candidates due to their low ionic migration and small dark current. Fabrication methods, including pressing, membrane filling, blade coating, spray coating
etc.
, will be summarized and discussed in detail. This feature article discusses the potential and challenges in perovskite X-ray detection and imaging, providing new research directions for future development.
Halide perovskites are developed to be sensitive, stable and scalable in the future commercialization process.
Bismuth vanadate (BiVO
) exhibits large absorption efficiency for hard X-rays, which endows it with a robust capacity to attenuate X-ray radiation across a broad energy range. The anisotropic ...properties of BiVO
allow for the manipulation of their physical and chemical characteristics through crystallographic orientation and exposed facets. In this study, the issue of heavy recombination caused by sluggish electron transport in BiVO
is successfully addressed by enhancing the abundance of the (040) crystal face ratio using a Co
crystal face exposure agent. The facet-dependent modifications exhibit excellent and balanced intrinsic charge transport properties, and finely optimize both the sensitivity and detection limit of BiVO
X-ray detectors. As a result, ultra-stable BiVO
metal oxide X-ray detectors demonstrate a high sensitivity of 3164 µC Gy
cm
and a low detection limit of 20.76 nGy
s
under 110 kVp hard X-rays, establishing a new benchmark for X-ray detectors based on polycrystalline Bi-halides and metal oxides. These findings highlight the significance of crystal orientation in optimizing materials for X-ray detection, setting a new sensitivity record for X-ray detectors based on polycrystalline Bi-halides and metal oxides, which paves the way for the development of advanced, low-dose, and highly stable imaging systems specifically for hard X-rays.
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Ferroelectric perovskites are recognized as promising candidates for use in optoelectronics due to the efficient electron and hole extraction enabled by the spontaneous electric polarization induced ...depolarization electric field. Ferroelectric perovskite oxides also show good stability in harsh chemical, mechanical, and thermal conditions and can be fabricated by using robust and scalable methods. However, the small photocurrent of the typical ferroelectric oxide optoelectronics greatly limits their applications, such as in photovoltaics and photocatalysis. Here, we show that ferroelectric perovskite oxides are suitable for low-dose X-ray detection (ultraweak radiation detection). Ferroelectric plate-like perovskite-type CaBi2Ta2O9 (CBTa), prepared by a solid-state sintered reaction method, displays a spontaneous polarization (P s) of 6.5 μC cm–2, a remanent polarization (P r) of 4.9 μC cm–2, and a high Curie temperature (T c) of 1196 K. Large resistivity and high P r of CBTa enable a good response to low-dose X-rays under zero bias, resulting in a detection limit of 30 nGyair s–1 for the detector, which is much lower than the requirement for X-ray diagnostics (5.5 μGyair s–1). The CBTa detectors also exhibit ultralow noise and good operation stability. This study will motivate new strategies to explore low-dose and stable X-ray detectors with ferroelectric oxides.
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The light weight, good bending resistance and low production cost make flexible perovskite solar cells (PSCs) good candidates in wearable electronics, portable charger, remote power, and flying ...objects. High power conversion efficiency (PCE) plays a crucial role on obtaining the high mass specific power of flexible devices. However, the performance for flexible PSCs is still having a large room to be improved. Here, we added the 2-amino-5-cyanopyridine (ACP) molecule with a polar electron density distribution in the perovskite precursor solution to improve the performance of flexible PSCs. The cyano groups with electron-withdrawing ability are expected to passivate positively charged point defects, while amines with electron donating ability are expected to passivate negatively charged point defects in perovskite films. Thanks to the effective passivation of defects at the grain boundary and surface of perovskite films, the PCE of flexible PSCs is obviously increased from 16.9% to 18.0%. These results provide a universal approach to improve performance of flexible PSCs by healing the defects in perovskite films through electrostatic interactions.
Flexible perovskite solar cell with power conversion efficiency of 18% is obtained by healing the defects in perovskite films through electrostatic interactions. Display omitted
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