title: Heavy metallic oxide nanoparticles for enhanced sensitivity in semiconducting polymer x-ray detectors.
abstract: Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices have a rather low detection sensitivity because of the low x-ray attenuation efficiency of the organic active layer. Here, we demonstrate a way to overcome this limitation through the introduction of high density nanoparticles having a high atomic number (Z) to increase the x-ray attenuation. Specifically, bismuth oxide (Bi(2)O(3)) nanoparticles (Z = 83 for Bi) are added to a poly(triarylamine) (PTAA) semiconducting polymer in the active layer of an x-ray detector. Scanning electron microscopy (SEM) reveals that the Bi(2)O(3) nanoparticles are reasonably distributed in the PTAA active layer. The reverse bias dc current-voltage characteristics for PTAA-Bi(2)O(3) diodes (with indium tin oxide (ITO) and Al contacts) have similar leakage currents to ITO/PTAA/Al diodes. Upon irradiation with 17.5 keV x-ray beams, a PTAA device containing 60 wt% Bi(2)O(3) nanoparticles demonstrates a sensitivity increase of approximately 2.5 times compared to the plain PTAA sensor. These results indicate that the addition of high-Z nanoparticles improves the performance of the dosimeters by increasing the x-ray stopping power of the active volume of the diode. Because the Bi(2)O(3) has a high density, it can be used very efficiently, achieving a high weight fraction with a low volume fraction of nanoparticles. The mechanical flexibility of the polymer is not sacrificed when the inorganic nanoparticles are incorporated.
authors.affiliation: Energy Research Centre, Maejo University, Chiang Mai, Thailand. a.intaniwet@hotmail.co.th
authors.forename: A
authors.initials: A
authors.lastname: Intaniwet
authors.forename: C A
authors.initials: CA
authors.lastname: Mills
authors.forename: M
authors.initials: M
authors.lastname: Shkunov
authors.forename: P J
authors.initials: PJ
authors.lastname: Sellin
authors.forename: J L
authors.initials: JL
authors.lastname: Keddie
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D053768:Metal Nanoparticles / Q000528:radiation effects*; D019216:Metals, Heavy / Q000528:radiation effects*; D010087:Oxides / Q000528:radiation effects; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation*; D012666:Semiconductors; D012680:Sensitivity and Specificity; D014965:X-Rays
chemical_list: D019216:Metals, Heavy; D010087:Oxides