Sensitivity analysis of X-ray detectors based on BFE and MEH-PPV organic sensor

In this work we fabricated flexible cells of organic devices in which layers of poly [9,9´-dioctyl-fluorene-2,7-diyl]-copoly[diphenyl-p-tolyl-amine-4,4´-diyl] (BFE) and poly[lmethoxy-4-(2-ethylhexyloxy)-phenylenevinylene] (MEH-PPV) were deposited on Indium Tin Oxide (ITO) coated Polyethylene terephtalate (PET) substrates. In addition to investigating MEHPPV organic sensors, this research has introduced a novel X-ray detector based on BFE organic sensor. BFE hasn´t been applied in X-ray sensors and in this paper we use this organic material to fabricate a new electronic device. Devices were being exposed to X-ray source which normally operates at 60 kV or 70 kV for medical applications. Device fabrication followed a planar structure in which a thick layer of polymer was sandwiched between two metal electrodes. Based on experiments performed at room temperature, we found out that BFE-based structure proves to be much more stable in comparison to its MEH-PPV-based counterpart. It also maintained almost the same photocurrent in a four months time frame after fabrication. The operation mechanism of the device is described by photoconductive phenomenon of X-ray detectors based on organic materials. The response time of the device is 53 ms. All photocurrent measurements were done under the application of a 170 kV/cm electric field. Corresponding results indicated that AI/BFE better contributes to the formation of a rectifying contact than that of AI/MEH-PPV. Utilization of BFE in organic sensor fabrication generated such electronic devices that don´t have the weaknesses of RVG (radiovisiography) silicon sensors (i.e. inflexibility, instability against moisture) and could be very helpful in medical radiography applications.