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2D layered hybrid perovskites have recently attracted an increasing interest as active layers in LEDs and UV–Vis photodetectors. 2D perovskites crystallize in a natural self‐assembled quantum well‐like structure and possess several interesting features among which low‐temperature (<100 °C) synthesis and low defect density. Here are presented solid‐state ionizing radiation direct detectors based on the 2D layered hybrid perovskite PEA2PbBr4 (PEA = C6H5C2H4NH3+) deposited from solution using scalable techniques and directly integrated onto a pre‐patterned flexible substrate in the form of micro‐crystalline films displaying crystal‐like behavior, as evidenced by the ultra‐fast (sub‐microsecond) and good detection performances under UV light. The effective detection of X‐rays (up to 150 kVp) is demonstrated with sensitivity values up to 806 µC Gy−1 cm−2 and Limit of Detection of 42 nGy s−1, thus combining the excellent performance for two relevant figures of merit for solid‐state detectors. Additionally, the tested devices exhibit exceptionally stable response under constant irradiation and bias, assessing the material robustness and the intimate electrical contact with the electrodes. PEA2PbBr4 micro‐crystalline films directly grown on flexible pre‐patterned substrate open the way for large‐area solid‐state detectors working at low radiation flux for ultra‐fast X‐ray imaging and dosimetry. [ABSTRACT FROM AUTHOR]

The demand for high‐energy radiation detection systems combining high sensitivity, low‐cost and large‐area fabrication has pushed the research on hybrid perovskites as promising materials for X‐ and γ‐photon detection, thanks to their high Z atoms, solution‐processability, and high optoelectronic performance. Here, flexible direct X‐ray detectors are demonstrated with outstanding real‐time detection properties. They are based on printed micrometers‐thick films of methylammonium lead triiodide nanocrystals inks, formulated in low boiling point and benign solvents. Record optoelectronic performances, such as high X‐ray sensitivity (up to 2270 µC Gy−1 cm−2), radiation tolerance over 2.2 Gy of total dose, and fast response time (48 ms) have been achieved by using a simple device architecture and materials processing The functionality under strong bending stress (strain > 10%) and under high X‐ray energy (up to 150 keV) has been assessed, opening the way for flexible real‐time direct radiation detectors and imagers, operating at low‐voltages (bias < 4V) and apt to be fabricated by means of large‐area scalable processes. [ABSTRACT FROM AUTHOR]

The recent years witnessed an unprecedented enhancement in improved functionality materials and in the sophistication of solution‐based device fabrication techniques. Such significant advancements lead to unexpected and effective opportunities for the utilization of solution‐grown organic materials and perovskites in the detection of ionizing radiation. This review presents an updated overview of the recently reported top performing and more innovative organic/perovskite‐based X‐ray detectors, providing a comparison and a critical discussion on the different materials' properties and performance. Solution‐growth methods that allow to obtain detector grade electronic materials are discussed, focusing on the growth both of single crystals and of thin/thick films and foreseeing the implementation of large‐area, organic/hybrid‐, and perovskite‐based radiation detectors. Insights into the X‐ray detection mechanisms are provided, detailing the fundamental processes involved in the charge collection and in the photoconductive gain model, together with the typical figures of merit that describe radiation detector performance. [ABSTRACT FROM AUTHOR]

Herein, a simple, solvent‐free method to fabricate polymer‐encapsulated halide perovskite photoconductors is described. Dry mechanochemical synthesis is used to prepare CsPbBr3 in the presence of poly(butyl methacrylate) (PBMA). The resulting composite powder is then heated and pressed into a free‐standing disk with a thickness controlled by a metallic spacer ring. The disk can be laminated on a glass substrate patterned with interdigitated electrodes, resulting in a planar photoconductor device. The best photoconductive performance is obtained for disks that consist of 75 wt.% CsPbBr3 in PBMA, reaching a detectivity of ≈2 × 1011 Jones. Moreover, by adjusting the thickness of the disk, narrowband detectors can be obtained due to charge collection narrowing. Depending on the thickness of the pressed disk, the position and width of the detectivity peak can be tuned. At last, the disks are tested as possible absorber materials for X‐ray detectors, where ow detection limit, and fast and linear response are measured for perovskite‐polymer disks with 50 wt.% perovskite content. This work shows a simple and versatile approach toward the fabrication of halide perovskite photodetectors, which can be carried out in air and without the use of solvents. [ABSTRACT FROM AUTHOR]

In this work we report the results on the investigation of rubrene single crystals as solid state direct ionizing radiation detectors. With the aim to understand how electrical properties, and in particular a large charge carrier mobility, affect the radiation detection process in organic semiconducting single crystals, we compare the detection performance of rubrene-based devices with those of 1,5-dinitronaphthalene (DNN)-based ones. DNN has been recently proven to be a stable and reliable X-ray direct detector, operating at very low voltages, in air and at room temperature, with a carrier mobility values about two orders of magnitude lower than rubrene. We demonstrate here that the large charge carrier mobility of rubrene crystals does not result in a better X-rays detection performance. In fact, rubrene devices are shown to be less performing than DNN as detectors, with lower sensitivity to X-rays, poorer stability and reproducibility, and longer rise and decay times of the signal. [ABSTRACT FROM AUTHOR]

Organic semiconductors are excellent candidates for X‐ray detectors that can adapt to new applications, with unique properties including mechanical flexibility and the ability to cover large surfaces. Their chemical composition, primarily carbon and hydrogen, makes them human tissue equivalent in terms of radiation absorption. This is a highly desirable property for a radiation dosimeter to be employed in medical diagnostics and therapy, however a low‐Z composition limits the absorption of ionizing radiation. The detection efficiency can be enhanced by considering the photoconductive gain (PG) effect, a significant contributor to the ionizing radiation detection mechanism in this class of materials. In this work, a process of controlled solution deposition by nozzle printing and crystallization of an organic semiconductor thin film is demonstrated whereby a flexible, arrayed thin‐film X‐ray detector with record X‐ray sensitivities among flexible radiation detectors (S = (9.0 ± 0.4) × 107 µC Gy−1 cm−3) is developed. The excitonic peaks responsible for the activation of the PG effect are investigated and identified using a novel technique called photocurrent spectroscopy optical quenching, and the analysis of the changes in trap states is further demonstrated. [ABSTRACT FROM AUTHOR]

Metal halide perovskite photodiodes have garnered extensive attention owing to their favorable optoelectronic properties, rendering them attractive for visible, near‐infrared, and X‐ray sensors. However, their predominant reliance on solution‐processing deposition techniques poses challenges for seamless integration into existing industrial processes. In this study, this limitation is addressed by developing fully vacuum‐processed perovskite photodiodes with varying hole transport layers (HTL). These findings underscore the critical role of HTL selection in influencing the dark and noise current characteristics of the diodes. With an optimized HTL, photodiodes are obtained with low noise current (≈3 10−14 A Hz−1/2) and high specific detectivity (≈1012 Jones at 710 nm at −0.5 V). The photodiodes are also tested as X‐ray detectors and are found to be stable under X‐ray radiation, with state‐of‐the‐art sensitivity of 33 ± 4 µC Gy−1 cm−2 and a low limit of detection of 2.0 ± 1.6 µG s−1. These insights contribute to the development of perovskite photodiodes with improved performance and broader industrial applicability. [ABSTRACT FROM AUTHOR]

The attention focused on the application of organic electronics for the detection of ionizing radiation is rapidly growing among the international scientific community, due to the great potential of organic technology to enable large‐area conformable sensor panels. However, high‐energy photon absorption is challenging as organic materials are constituted of atoms with low atomic numbers. Here it is reported how, by synthesizing new solution‐processable organic molecules derived from 6,13‐bis(triisopropylsilylethynyl)pentacene (TIPS‐pentacene) and 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene, with Ge‐substitution in place of the Si atoms to increase the material atomic number, it is possible to boost the X‐ray detection performance of organic thin films on flexible plastic substrates. Bis(triisopropylgermylethynyl)‐pentacene based flexible organic thin film transistors show high electrical performance with higher mobility (0.4 cm2 V−1 s−1) and enhanced X‐ray sensitivity, up to 9.0 × 105 µC Gy−1 cm−3, with respect to TIPS‐pentacene‐based detectors. Moreover, similar results are obtained for 5,11‐bis(triethylgermylethynyl)anthradithiophene devices, confirming that the proposed strategy, that is, increasing the atomic number of organic molecules by chemical tailoring to improve X‐ray sensitivity, can be generalized to organic thin film detectors, combining high X‐ray absorption, mechanical flexibility, and large‐area processing. [ABSTRACT FROM AUTHOR]

Organic semiconductors are a promising material candidate for X‐ray detection. However, the low atomic number (Z) of organic semiconductors leads to poor X‐ray absorption thus restricting their performance. Herein, the authors propose a new strategy for achieving high‐sensitivity performance for X‐ray detectors based on organic semiconductors modified with high –Z heteroatoms. X‐ray detectors are fabricated with p‐type organic semiconductors containing selenium heteroatoms (poly(3‐hexyl)selenophene (P3HSe)) in blends with an n‐type fullerene derivative ([6,6]‐Phenyl C71 butyric acid methyl ester (PC70BM). When characterized under 70, 100, 150, and 220 kVp X‐ray radiation, these heteroatom‐containing detectors displayed a superior performance in terms of sensitivity up to 600 ± 11 nC Gy−1 cm−2 with respect to the bismuth oxide (Bi2O3) nanoparticle (NP) sensitized organic detectors. Despite the lower Z of selenium compared to the NPs typically used, the authors identify a more efficient generation of electron‐hole pairs, better charge transfer, and charge transport characteristics in heteroatom‐incorporated detectors that result in this breakthrough detector performance. The authors also demonstrate flexible X‐ray detectors that can be curved to a radius as low as 2 mm with low deviation in X‐ray response under 100 repeated bending cycles while maintaining an industry‐standard ultra‐low dark current of 0.03 ± 0.01 pA mm−2. [ABSTRACT FROM AUTHOR]

This study reports on a novel, flexible, proton beam detector based on mixed 3D–2D perovskite films deposited by solution onto thin plastic foils. The 3D–2D mixture allows to obtain micrometer‐thick and highly uniform films that constitute the detector's active layer. The devices demonstrate excellent flexibility with stable electric transport properties down to a bending radius of 3.1 mm. The detector is characterized under a 5 MeV proton beam with fluxes in the range [4.5 × 105 – 1.4 × 109] H+ cm−2 s−1, exhibiting a stable response to repetitive irradiation cycles with sensitivity up to (290 ± 40) nC Gy−1mm−3 and a limit of detection down to (72±2) µGy s−1. The detector radiation tolerance is also assessed up to a total of 1.7 × 1012 protons impinging on the beam spot area, with a maximum variation of the detector's response of 14%. [ABSTRACT FROM AUTHOR]

Curved X‐ray detectors have the potential to revolutionize diverse sectors due to benefits such as reduced image distortion and vignetting compared to their planar counterparts. While the use of inorganic semiconductors for curved detectors are restricted by their brittle nature, organic–inorganic hybrid semiconductors which incorporated bismuth oxide nanoparticles in an organic bulk heterojunction consisting of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and [6,6]‐phenyl C71 butyric acid methyl ester (PC70BM) are considered to be more promising in this regard. However, the influence of the P3HT molecular weight on the mechanical stability of curved, thick X‐ray detectors remains less well understood. Herein, high P3HT molecular weights (>40 kDa) are identified to allow increased intermolecular bonding and chain entanglements, resulting in X‐ray detectors that can be curved to a radius as low as 1.3 mm with low deviation in X‐ray response under 100 repeated bending cycles while maintaining an industry‐standard dark current of <1 pA mm−2 and a sensitivity of ≈ 0.17 μC Gy−1 cm−2. This study identifies a crucial missing link in the development of curved detectors, namely the importance of the molecular weight of the polymer semiconductors used. [ABSTRACT FROM AUTHOR]

X‐ray detectors play a pivotal role in development and advancement of humankind, from far‐reaching impact in medicine to furthering the ability to observe distant objects in outer space. While other electronics show the ability to adapt to flexible and lightweight formats, state‐of‐the‐art X‐ray detectors rely on materials requiring bulky and fragile configurations, severely limiting their applications. Lead halide perovskites is one of the most rapidly advancing novel materials with success in the field of semiconductor devices. Here, an ultraflexible, lightweight, and highly conformable passively operated thin film perovskite X‐ray detector with a sensitivity as high as 9.3 ± 0.5 µC Gy−1 cm−2 at 0 V and a remarkably low limit of detection of 0.58 ± 0.05 μGy s−1 is presented. Various electron and hole transporting layers accessing their individual impact on the detector performance are evaluated. Moreover, it is shown that this ultrathin form‐factor allows for fabrication of devices detecting X‐rays equivalently from front and back side. [ABSTRACT FROM AUTHOR]

Purpose: The development of novel detectors for dosimetry in advanced radiotherapy modalities requires materials that have a water equivalent response to ionizing radiation such that characterization of radiation beams can be performed without the need for complex calibration procedures and correction factors. Organic semiconductors are potentially an ideal technology in fabricating devices for dosimetry due to tissue equivalence, mechanical flexibility, and relatively cheap manufacturing cost. The response of a commercial organic photodetector (OPD), coupled to a plastic scintillator, to ionizing radiation from a linear accelerator and orthovoltage x‐ray tube has been characterized to assess its potential as a dosimeter for radiotherapy. The radiation hardness of the OPD has also been investigated to demonstrate its longevity for such applications. Methods: Radiation hardness measurements were achieved by observing the response of the OPD to the visible spectrum and 70 keV x rays after pre‐exposure to 40 kGy of ionizing radiation. The response of a preirradiated OPD to 6‐MV photons from a linear accelerator in reference conditions was compared to a nonirradiated OPD with respect to direct and indirect (RP400 plastic scintillator) detection mechanisms. Dose rate dependence of the OPD was measured by varying the surface‐to‐source distance between 90 and 300 cm. Energy dependence was characterized from 29.5 to 129 keV with an x‐ray tube. The percentage depth dose (PDD) curves were measured from 0.5 to 20 cm and compared to an ionization chamber. Results: The OPD sensitivity to visible light showed substantial degradation of the broad 450 to 600 nm peak from the donor after irradiation to 40 kGy. After irradiation, the spectral shape has a dominant absorbance peak at 370 nm, as the acceptor better withstood radiation damage. Its response to x rays stabilized to 30% after 35 kGy, with a 0.5% difference between 770 Gy increments. The OPD exhibited reproducible detection of ionizing radiation when coupled with a scintillator. Indirect detection showed a linear response from 25 to 500 cGy and constant response to dose rates from 0.31 Gy/pulse to 3.4 × 10−4 Gy/pulse. However, without the scintillator, response increased by 100% at low dose rates. Energy independence between 100 keV and 1.2 MeV advocates their use as a dosimeter without beam correction factors. A dependence on the scintillator thickness used during a comparison of the PDD to the ionizing chamber was identified. A 1‐mm‐thick scintillator coupled with the OPD demonstrated the best agreement of ± 3%. Conclusions: The response of OPDs to ionizing radiation has been characterized, showing promising use as a dosimeter when coupled with a plastic scintillator. The mechanisms of charge transport and trapping within organic materials varies for visible and ionizing radiation, due to differing properties for direct and indirect detection mechanisms and observing a substantial decrease in sensitivity to the visible spectrum after 40 kGy. This study proved that OPDs produce a stable response to 6‐MV photons, and with a deeper understanding of the charge transport mechanisms due to exposure to ionizing radiation, they are promising candidates as the first flexible, water equivalent, real‐time dosimeter. [ABSTRACT FROM AUTHOR]

Materials and technology development for designing innovative and efficient X‐ray radiation detectors is of utmost importance for a wide range of applications ranging from security to medical imaging. Here, highly sensitive direct X‐ray detectors based on novel cesium (Cs)‐based triple cation mixed halide perovskite thin films are reported. Despite being in a thin film form, the devices exhibit a remarkably high X‐ray sensitivity of (3.7 ± 0.1) µC Gy−1 cm−2 under short‐circuit conditions. At a small reverse bias of 0.4 V, the sensitivity further increases by orders of magnitude reaching a record value of (97 ± 1) µC Gy−1 cm−2 which surpasses state‐of‐the‐art inorganic large‐area detectors (a‐Se and poly‐CZT). Based on detailed structural, electrical, and spectroscopic investigations, the exceptional sensitivity of the triple cation Cs perovskite is attributed to its high ambipolar mobility‐lifetime product as well as to the formation of a pure stable perovskite phase with a low degree of energetic disorder, due to an efficient solution‐based alloying of individual n‐ and p‐type perovskite semiconductors. [ABSTRACT FROM AUTHOR]

A circuit based on low voltage Organic Field-Effect Transistors (OFETs) and conceived for monitoring the security check history of luggage in airport environment is reported. An OFET-based, direct X-Rays detector is used as sensing element and integrated in an organic circuit for digitization and memorization of the X-Ray exposure event. An integrated interface to a commercial RFID chip and antenna is also realized to allow remote readout of the circuit status. The operation mechanism of the circuit is described and a complete explanation of the strategy adopted for circuit design is reported. Simulations of the systems in Cadence ® Virtuoso environment are presented: X-Ray response of the sensor is modelled, and the overall functionality of the detection and memorization schema are demonstrated. Fabrication and characterization of the circuit under X-Rays in laboratory environment are described. In particular, the correct functionality of the circuit is demonstrated, as well as its actual capability in driving the commercial RFID tag system. The robustness of the circuit to aging and exposure to X-Rays in operation conditions is finally discussed. [ABSTRACT FROM AUTHOR]