Search

Ionizing radiations are important tools employed every day in the modern society. For example, in medicine they are routinely used for diagnostic and therapy. The large variety of applications leads to the need of novel, more efficient, low-cost ionizing radiation detectors with new functionalities. Personal dosimetry would benefit from wearable detectors able to conform to the body surfaces. Traditional semiconductors used for ionizing radiation direct detectors offer high performance but they are intrinsically stiff, brittle and require high voltages to operate. Hybrid lead-halide perovskites emerged recently as a novel class of materials for ionizing radiation detection. They combine high absorption coefficient, solution processability and high charge transport capability, enabling efficient and low-cost detection. The deposition from solution allows the fabrication of thin-film flexible devices. In this thesis, I studied the detection properties of different types of hybrid perovskites, deposited from solution in thin-film form, and tested under X-rays, gamma-rays and protons beams. I developed the first ultraflexible X-ray detector with exceptional conformability. The effect of coupling organic layers with perovskites was studied at the nanoscale giving a direct demonstration of trap passivation effect at the grain boundaries. Different perovskite formulations were deposited and tested to improve the film stability. I report about the longest aging studies on perovskite X-ray detectors showing that the addition of starch in the precursors’ solution can improve the stability in time with only a 7% decrease in sensitivity after 630 days of storage in ambient conditions. 2D perovskites were also explored as direct detector for X-rays and gamma-rays. Detection of 511 keV photons by a thin-film device is here demonstrated and was validated for monitoring a radiotracer injection. At last, a new approach has been used: a 2D/3Dmixed perovskite thin-film demonstrated to

Ionizing radiation detection is of extreme importance for a large number of applications. X-rays are widely used in research as well as in medical diagnostic, therapy and public security. The largest demand for X-ray detectors comes from the medical field, where new low-cost materials enabling high sensitivity devices are needed to reduce the incident dose to the patient. Flexible devices, able to adapt itself to the patient's skin, can be used during continuous radiography monitoring. Such devices will improve patient comfort, portability and versatility of the diagnostic techniques. Solution-processed organometallic lead-halide perovskites are good candidates for the development of flexible X-ray detectors. The combination of high attenuation coefficient, due to the presence of heavy elements, and good electronic properties allows the fabrication of thin-film devices with high sensitivity. Moreover, these materials can be processed by the solution at low temperature enabling the possibility for low-cost large-area detectors. In this work a triple cation mixed halide perovskite, combined with a 1,4 micron thick PET, was used to create ultra-flexible direct X-ray detectors. The devices were tested under X-ray radiation up to 150keV showing a maximum normalized sensitivity of 10,6\pm0,8nCmGy^{-1}cm^{-2} and a limit of detection of 9,9\pm0,2\mu Gy/s, thus demonstrating the possibility of low-cost ultra-flexible passive X-ray detectors.

La grande importanza della ricerca di materiali innovativi da impiegare come detector di raggi X è dovuta al loro utilizzo in svariati campi, dalla ricerca scientifica alla medicina, dove sono richiesti nuovi rivelatori a basso costo e a grande area. Questo spinge la ricerca ad indagare le perovskiti organometalliche che sembrano soddisfare i requisiti necessari per nuovi detector. Esse infatti possiedono un elevato assorbimento delle radiazioni ad alta energia e processabilità in fase liquida. In questa tesi sono state analizzate due perovskiti depositate da soluzione: MAPbI3 e CsMAFAPb(IBr)3. In particolare esse costituiscono lo strato attivo di due diverse tipologie di detector: fotoconduttori e celle solari. Viene dimostrato come tali dispositivi presentino una elevata sensibilità alla radiazione X e come essi possano essere impiegati come rivelatori altamente efficienti a film sottile.

Ionizing radiation detection is of extreme importance for a large number of applications. X-rays are widely used in research as well as in medical diagnostic, therapy and public security. The largest demand for X-ray detectors comes from the medical field, where new low-cost materials enabling high sensitivity devices are needed to reduce the incident dose to the patient. Flexible devices, able to adapt itself to the patient's skin, can be used during continuous radiography monitoring. Such devices will improve patient comfort, portability and versatility of the diagnostic techniques. Solution-processed organometallic lead-halide perovskites are good candidates for the development of flexible X-ray detectors. The combination of high attenuation coefficient, due to the presence of heavy elements, and good electronic properties allows the fabrication of thin-film devices with high sensitivity. Moreover, these materials can be processed by the solution at low temperature enabling the possibility for low-cost large-area detectors. In this work a triple cation mixed halide perovskite, combined with a 1,4 micron thick PET, was used to create ultra-flexible direct X-ray detectors. The devices were tested under X-ray radiation up to 150keV showing a maximum normalized sensitivity of 10,6\pm0,8nCmGy^{-1}cm^{-2} and a limit of detection of 9,9\pm0,2\mu Gy/s, thus demonstrating the possibility of low-cost ultra-flexible passive X-ray detectors.

La grande importanza della ricerca di materiali innovativi da impiegare come detector di raggi X è dovuta al loro utilizzo in svariati campi, dalla ricerca scientifica alla medicina, dove sono richiesti nuovi rivelatori a basso costo e a grande area. Questo spinge la ricerca ad indagare le perovskiti organometalliche che sembrano soddisfare i requisiti necessari per nuovi detector. Esse infatti possiedono un elevato assorbimento delle radiazioni ad alta energia e processabilità in fase liquida. In questa tesi sono state analizzate due perovskiti depositate da soluzione: MAPbI3 e CsMAFAPb(IBr)3. In particolare esse costituiscono lo strato attivo di due diverse tipologie di detector: fotoconduttori e celle solari. Viene dimostrato come tali dispositivi presentino una elevata sensibilità alla radiazione X e come essi possano essere impiegati come rivelatori altamente efficienti a film sottile.