Fabrication of Alq3/PMMA nanocomposite sheet and its potential applications as radiation dosimeter

Abstract

Tris (8-hydroxyquinoline) aluminum (Alq3) is a highly luminescent organometallic compound, and therefore has numerous applications in electronic devices. Its unique optical property is suitable for organic light-emitting diodes, optoelectronic, and photodiodes. Despite its numerous potentials, no study investigated its response to ionizing radiation, particularly in its nanostructure form. In this work Alq3 were incorporated in a highly transparent polymethyl methacrylate (PMMA) polymer sheet using chloroform as a proper solvent for both materials. The ratio of Alq3 to PMMA powders was fixed at 1:10. The resulting composite showed recrystallized fine nanoparticles of Alq3, uniformly embedded in the PMMA sheet. Then small pieces of this nanocomposite sheet were exposed to various doses of X-ray and electron beam (E-beam) radiation doses in the range of 5–20 Gy. The molecular fingerprint and optical emission properties of the pristine and irradiated nanocomposite sheets were evaluated using Raman and PL spectroscopy. A systematic increase in the PL and Raman signals with increasing radiation doses were recorded. In addition, blueshift in the PL peak positions of nearly 6 and 9 nm for X-ray and E-beam irradiated sheets, respectively were also observed. These increments were attributed to the formation of radiative vacancies in the Alq3 molecules while the blueshift might be related to possible weakening of some of the Alq3 bonds such as C-O, C-C, C-H and Al-O, respectively. Therefore, the systematic changes in the optical properties might serve as preliminary parameters to investigate its potential use in radiation dosimetry following its nearly excellent linear dose dependence on signal intensities, which are quite encouraging.