Hybrid organic photodetectors for radiography

Most of todays X-ray detectors are using an indirect conversion mechanism. The X-ray radiation is converted into visible light within a thick scintillator layer. The visible light is then absorbed by standard thin-film photodetectors. The isotropic propagation of light in the scintillator reduces the resolution of the x-ray imager. This work avoids the stacked structure by integration of inorganic PbS quantum dots directly into the bulk hetero junction (BHJ) of an organic photodetector. X-ray photons are immediately converted into charge carriers and travel in direction of the electrical field towards the electrodes. However, this concept demands much thicker organic layers than known from conventional OLED and OPV processing. We demonstrate that thick diodes can be achieved with a spray coating process and the influence of spraying parameters on device performance is discussed.