title: Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V.
abstract: The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104and 77,000 nC mGy-1cm-3, respectively.
authors.affiliation: Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Basiricò
authors.affiliation: Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy.
authors.forename: Andrea
authors.identifier: http://orcid.org/0000-0002-7877-7739
authors.initials: A
authors.lastname: Ciavatti
authors.affiliation: Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy.
authors.forename: Tobias
authors.initials: T
authors.lastname: Cramer
authors.affiliation: Department of Electrical and Electronic Engineering, University of Cagliari, Piazza D'Armi, Cagliari 09123, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Cosseddu
authors.affiliation: Department of Electrical and Electronic Engineering, University of Cagliari, Piazza D'Armi, Cagliari 09123, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Bonfiglio
authors.affiliation: Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Fraboni