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 Gy 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.
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.
A flexible, fully organic detector for proton beams is presented here. The detector operates in the indirect mode and is composed of a polysiloxane-based scintillating layer coupled to an organic phototransistor, that is assessed for flexibility and low-voltage operation (V = −1 V), with a limit of detection of 0.026 Gy min−1. We present a kinetic model able to precisely reproduce the dynamic response of the device under irradiation and to provide further insight into the physical processes controlling it. This detector is designed to target real-time and in-situ dose monitoring during proton therapy and demonstrates mechanical flexibility and low power operation, assessing its potential employment as a personal dosimeter with high comfort and low risk for the patient. The results show how such a proton detector represents a promising tool for real-time particle detection over a large area and irregular surfaces, suitable for many applications, from experimental scientific research to innovative theranostics.
High sensitivity and efficient X‐ray detectors are needed to promote and boost their application as tools in medical diagnostics and radiotherapy. Lead halide perovskites have emerged recently as a novel class of material for efficient X‐ray detection. Although 3D perovskites possess very interesting optoelectronic properties they suffer from low environmental and operational stability. Here a strategy based on using starch as a polymeric template for the fabrication of stable thin film perovskite X‐ray detectors is reported. The proposed p‐i‐n photodiodes can operate with no external bias applied (fully passive devices), reaching a top sensitivity of 5.5 ± 0.2 µC Gy−1 s−1. The device degradation is monitored for samples stored in air for a time window of 630 days, demonstrating exceptional stability: 97% of the initial sensitivity is retained for the best perovskite‐starch composite formulation making it the most stable unencapsulated perovskite X‐ray detector reported so far.
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 × 10 5 -1.4 × 10 9 ] H + cm −2 s −1 , exhibiting a stable response to repetitive irradiation cycles with sensitivity up to (290 ± 40) nC Gy −1 mm −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 × 10 12 protons impinging on the beam spot area, with a maximum variation of the detector's response of 14%.
X‐ray direct detectors based on hybrid lead‐halide perovskite have seen a dramatic increase of interest in the last years. A rush for the achievement of high performing devices drives the scientific community. In this context, several photoconductor sensors employ functional layers to increase the gain effect, but the full comprehension of the mechanism is still lacking. Here X‐ray nanoanalysis is used, performed by simultaneous acquisition of X‐ray Fluorescence and X‐ray Beam Induced Current maps, to investigate at the nanoscale level the role of [6,6]‐phenyl‐C61‐butyric acid methyl ester fullerene (PCBM) molecules when interacting with MAPbI3 polycrystalline thin films acting as photo‐conductors in X‐ray detectors. At the device‐scale level it shows that the addition of PCBM enhances the X‐ray sensitivity by four times. At the nanoscale level how the perovskite grain boundaries act as high photocurrent generation centers is demonstrated. The addition of the PCBM increases the photocurrent generation, as the macroscopic performance does, and the charge collection becomes uniform over the full crystallite volume. The results clarify the role of grain boundaries and charge selecting layers and establish the X‐ray nanoanalysis techniques as a powerful tool to investigate charge transport and collection in perovskite films.
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