Published online by Cambridge University Press: 17 October 2011
We synthesize a series of polyvinylcarbazole (PVK) monoliths containing varying loadings of triphenyl bismuth as a high-Z dopant and varying fluors, either organic or organometallic, in order to study their use as scintillators capable of gamma ray spectroscopy. A trend of increasing bismuth loading resulting in a better resolved photopeak is observed. For PVK parts with no fluor or a standard organic fluor, diphenylanthracene (DPA), increasing bismuth loading results in decreasing light yield while with samples 1 or 3 % by weight of the triplet harvesting organometallic fluor bis(4,6-difluoropyridinato-N,C2)picolinatoiridium (FIrpic) show increasing light yield with increasing bismuth loading. Our best performing PVK/ BiPh3/FIrpic scintillator with 40 wt % BiPh3 and 3 wt % FIrpic has an emission maximum of 500 nm, a light yield of ∼30,000 photons/MeV, and energy resolution better than 7% FWHM at 662 keV. Replacing the Ir complex with an equal weight of DPA produces a sample with a light yield of ∼6,000 photons/MeV, with an emission maximum at 420 nm and energy resolution of 9% at 662 keV. Transmission electron microscopy studies show that the BiPh3 forms small clusters of approximately 5 nm diameter.