Organic semiconductor materials exhibit a great potential for the realization of large-area solution-processed devices able to directly detect high-energy radiation. However, only few works investigated on the mechanism of ionizing radiation detection in this class of materials, so far. In this work we investigate the physical processes behind X-ray photoconversion employing bis-(triisopropylsilylethynyl)-pentacene thin-films deposited by bar-assisted meniscus shearing. The thin film coating speed and the use of bis-(triisopropylsilylethynyl)-pentacene:polystyrene blends are explored as tools to control and enhance the detection capability of the devices, by tuning the thin-film morphology and the carrier mobility. The soobtained detectors reach a record sensitivity of 1.3 • 10 4 µC/Gy•cm 2 , the highest value reported for organic-based direct X-ray detectors and a very low minimum detectable dose rate of 35 µGy/s. Thus, the employment of organic large-area direct detectors for X-ray radiation in real-life applications can be foreseen.

The attention 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 the 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-5,11bis(triethylsilylethynyl)anthradithiophene (diF-TES-ADT), 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. TIPGe-pentacene based flexibleOTFTs show high electrical performance with higher mobility (0.4 cm 2 V -1 s -1 ) and enhanced X-ray sensitivity, up to 9.0 x 10 5 µC Gy -1 cm -3 , with respect to TIPS-pentacene based detectors. Moreover, similar results are obtained for diF-TEG-ADT devices, confirming that the proposed strategy, i.e.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.

We present a novel microelectronic x-ray dosimeter compatible with flexible plastic substrates and passive RFID detection.

The aim of this study is to assess direct X-ray detectors based on organic thin films, fabricated onto flexible plastic substrates, and operating at ultra-low bias (<1 V), for different medical applications. With this purpose, flexible fully organic pixelated X-ray detectors have been tested at the imaging beamline SYRMEP (SYnchrotron Radiation for MEdical Physics) at the Italian synchrotron Elettra, Trieste. The detectors' performance has been assessed for potential employment both as reliable wearable personal dosimeters for patients and as flexible X-ray medical imaging systems. A spatial resolution of 1.4 lp mm −1 with a contrast of 0.37 has been evaluated. Finally, we validate the detector using X-ray doses and energies typically employed for actual medical radiography, and using X-ray beam pulses provided by a commercial dental radiography system, recording a sensitivity of 1.6 × 10 5 µC Gy −1 cm −3 with a linear response with increasing of the dose rates and a reliable signal to 100 ms X-rays pulses.

The direct detection of 5-MeV protons by flexible organic detectors based on thin films is here demonstrated. The organic devices act as a solid-state detector, in which the energy released by the protons within the active layer of the sensor is converted into an electrical current. These sensors can quantitatively and reliably measure the dose of protons impinging on the sensor both in real time and in integration mode. This study shows how to detect and exploit the energy absorbed both by the organic semiconducting layer and by the plastic substrate, allowing to extrapolate information on the present and past irradiation of the detector. The measured sensitivity, S = (5.15 ± 0.13) pC Gy−1, and limit of detection, LOD = (30 ± 6) cGy s−1, of the here proposed detectors assess their efficacy and their potential as proton dosimeters in several fields of application, such as in medical proton therapy.

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.

The implementation of organic semiconductor (OSC) materials in X‐ray detectors provides exciting new opportunities for developing a new generation of biocompatible devices with high potential for the fabrication of sensitive and low‐cost X‐ray imaging systems. Here, the fabrication of high performance organic field‐effect transistors (OFETs) based on blends of 1,4,8,11‐tetramethyl‐6,13‐triethylsilylethynyl pentacene (TMTES) with polystyrene is reported. The films are printed employing a low cost and high‐throughput deposition technique. The devices exhibit excellent electrical characteristics with a high mobility and low density of hole traps, which is ascribed to the favorable herringbone packing (different from most pentacene derivatives) and the vertical phase separation in the blend films. As a consequence, an exceptional high sensitivity of (4.10 ± 0.05) × 1010 µC Gy–1cm–3 for X‐ray detection is achieved, which is the highest reported so far for a direct X‐ray detector based on a tissue equivalent full organic active layer, and is higher than most perovskite film‐based X‐ray detectors. As a proof of concept to demonstrate the high potential of these devices, an X‐ray image with sub‐millimeter pixel size is recorded employing a 4‐pixel array. This work highlights the potential exploitation of high performance OFETs for future innovative large‐area and highly sensitive X‐ray detectors for medical dosimetry and diagnostic applications.

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.