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Recoil nuclei produce high ionization and excitation densities in organic scintillators leading to reduced light yield via ionization quenching. To improve understanding of the relationship between organic scintillator specific luminescence and the characteristics of the recoil particle, this work evaluates proton and carbon light yield data using ionization quenching models over an energy range of tens of keV to several MeV for protons and 1-5 MeV for carbon ions. Previously-measured proton and carbon light yield data were examined for a variety of commercial and novel organic scintillating media: EJ-309, a liquid with pulse shape discrimination (PSD) properties; EJ-204, a fast plastic; EJ-276, a PSD-capable plastic; and a custom organic glass scintillator developed by Sandia National Laboratories. The canonical model of Birks did not adequately describe the ionization quenching behavior. Models proposed by Yoshida et al. and Voltz et al. provided a reasonable description of the proton light yield of a variety of organic scintillators over a broad energy range, but additional work is needed to extend the models to carbon ions. The impact of stopping power data was also investigated by comparing model predictions using SRIM and PSTAR/MSTAR libraries, and the results show a significant discrepancy for carbon ions. This work enhances understanding of ionization quenching and facilitates the accurate modeling of scintillator-based neutron detection systems relevant for medical physics, nuclear security and nonproliferation, and basic science studies.

Electrical double layer capacitors (EDLCs) featuring low-cost and solution-processable electrode materials have attracted significant research interest for their green and economical applications in energy harvesting and storage devices. Here, we demonstrate a novel synthetic route for films of an underexplored 3-D hexagonal bismuth chalcohalide, Bi13S18I2, and investigate its potential as the active electrode material in EDLC-type supercapacitors. The synthetic procedure has been optimised and comprises the lowest annealing temperature (150 °C) and the shortest processing time (1 h) currently reported. When integrated in a symmetrical EDLC with an aqueous NaClO4 electrolyte, the Bi13S18I2-based device achieves a remarkable areal capacitance of 210.68 mF cm−2 with 99.7% capacitance retention after 5000 cycles. Both the Bi13S18I2 powder and thin-film electrodes have been characterized through XRD, XPS, Raman spectroscopy, and SEM. The superior stability, low-cost, and facile synthesis of Bi13S18I2 proves its promising potential for supercapacitor applications.

Two organic–inorganic iodobismuthates, C5H6NBiI4 ([py][BiI4]) and C6H8NBiI4 ([mepy][BiI4]), have been prepared with their structures revealed by single-crystal X-ray diffraction. One-dimensional BiI4− anionic chains built by edge-sharing BiI6 octahedra were found in both materials; short I⋯I, I⋯C contacts and hydrogen bonding give rise to three-dimensional intermolecular interactions. Both compounds are semiconductors, with band gaps of around 2.0 eV, and the contribution from the organic moieties to the conduction band minimum has been derived by density functional theory. Solid-state optical and electrochemical studies performed on powders and thin films were carried out, and their stabilities under an ambient environment have been demonstrated. Their use as the absorber layer in printable mesoscopic solar cells without any hole transport material has led to efficiencies up to 0.9%, showing a promising new approach towards the development of lead-free third-generation photovoltaic materials.