For example, X‐rays are used in Biomedicine (Radiography), Radiotherapy (as a treatment for the therapy, including palliation, of cancer), Industrial quality control (automated inspection of industrial parts) and Security applications (control of luggages, cargos trucks and even people, before and during shipment by air, sea and road), and other niche but important applications in the scientific field (like X‐ray crystallography, X‐ray fluorescence, X‐ray photoelectron spectroscopy, Astronomy and Art ‐ paintings or sculptures are often X‐rayed to reveal features invisible to the naked eye, like under‐drawings, alterations, restorations, etc).
Many of these applications would take advantage of large area, thin and flexible ionizing radiation sensing systems able to operate at room temperature and to detect X‐rays in real time at affordable costs, but the technologies today available cannot deliver all these features in one single object.
Presently, the radiation detectors available on the market are either based on gas‐filled containers (like Geiger counters), on solid or liquid materials capable of producing visible photons upon exposure to the radiation (scintillators), or on solid materials capable of directly converting X‐ray photons into an electrical signal. The latter type of solid state sensors offers the great advantage to skip the need to employ two or more coupled devices (e.g. a scintillator and a photodiode or a photomultiplier tube), which grants satisfactory performances, but increases the device complexity (hence its maintenance and operating costs) and lowers its overall efficiency.
The state‐of‐the‐art solid state X‐ray detectors are based on inorganic materials (silicon, cadmium telluride, diamond, and the like), which indeed offer top detecting performances but are rigid, heavy, expensive, energy‐consuming, and often require low temperature cooling to work properly. Nonetheless, the market for X‐rays equipment, though not easy to estimate, according to publicly available documents was worth about $10 billions in 2008, with a steady growth per year of about 4‐6%. The key drivers for this growth were, and still are, the increasingly aging population, which demand for more and more radiography applications, the unavoidable transition from the rather obsolete photographic film technology to the digital one, the increasing security needs after the terrorist act of 9/11, and a strong demand for portable, robust and low‐cost X‐rays detectors. Therefore, there exists a very strong need to devise low‐cost, conformable, large area and reliable alternatives to the current technology radiation detectors; prospective low‐power consuming and portable (i.e. low weight and battery operated) sensing systems would have an even higher commercial success, since no such device is yet available or marketed.