Squaraine-based organic photodetector coupled to a scintillating crystal for X-ray sensing applications

To the aim of developing an X-ray imager based on a scintillator coupled to an organic photodetector, we fabricated and tested a detector pixel whose active material is a blend of squaraine dyes and Phenyl-C61-Butyric-Acid-Methyl-Ester (PCBM), processed to obtain a detector thickness of 2μm and a leakage current, at the operating voltage, below 10nA/cm2. The detector was coupled to a CsI(Tl) scintillator crystal obtaining, upon collimated 30keV x-ray beam, clear current signals of few hundreds of pA for a dose less than 5μGray/s, both in QCW and under 500μs long pulses. In addition, the development of the pixel on a flexible and transparent substrate leads to a better scintillator light collection.