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There is growing interest in the development of novel materials and devices capable of ionizing radiation detection for medical applications. Organic semiconductors are promising candidates to meet the demands of modern detectors, such as low manufacturing costs, mechanical flexibility, and a response to radiation equivalent to human tissue. However, organic semiconductors have typically been employed in applications that convert low energy photons into high current densities, for example, solar cells and LEDs, and thus existing design rules must be re-explored for ionizing radiation detection where high energy photons are converted into typically much lower current densities. In this work, we report the optoelectronic and X-ray dosimetric response of a tissue equivalent organic photodetector fabricated with solution-based inks prepared from polymer donor poly­(3-hexylthiophene) (P3HT) blended with either a non-fullerene acceptor (5Z,5′Z)-5,5′-((7,7′-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno­[1,2-b:5,6-b′]­dithiophene-2,7-diyl)­bis­(benzo­[c]­[1,2,5]­thiadiazole-7,4-diyl))­bis­(methanylylidene))­bis­(3-ethyl-2-thioxothiazolidin-4-one) (o-IDTBR) or a fullerene acceptor, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Indirect detection of X-rays was achieved via coupling of organic photodiodes with a plastic scintillator. Both detectors displayed an excellent response linearity with dose, with sensitivities to 6 MV photons of 263.4 ± 0.6 and 114.2 ± 0.7 pC/cGy recorded for P3HT:PCBM and P3HT:o-IDTBR detectors, respectively. Both detectors also exhibited a fast temporal response, able to resolve individual 3.6 μs pulses from the linear accelerator. Energy dependence measurements highlighted that the photodetectors were highly tissue equivalent, though an under-response in devices compared to water by up to a factor of 2.3 was found for photon energies of 30–200 keV due to the response of the plastic scintillator. The P3HT:o-IDTBR device exhibited a higher stability to radiation, showing just an 18.4% reduction in performance when exposed to radiation doses of up to 10 kGy. The reported devices provide a successful demonstration of stable, printable, flexible, and tissue-equivalent radiation detectors with energy dependence similar to other scintillator-based detectors used in radiotherapy.

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In recent times there has been a great deal of interest in the conversion of carbon dioxide into more useful chemical compounds. On the other hand, the translation of these developments in electrochemical reduction of carbon dioxide from the laboratory bench to practical scale remains an underexplored topic. Here we examine some of the major challenges, demonstrating some promising strategies towards such scale-up, including increased electrode area and stacking of electrode pairs in different configurations. We observed that increasing the electrode area from 1 to 10 cm2 led to only a 4% drop in current density, with similarly small penalties realised when stacking sub-cells together.

Selective oxidation of organic compounds is incredibly important in the production of a broad range of important chemicals. As such, these reactions attract a great deal of research attention, particularly where conventional synthesis uses harsh and corrosive reaction conditions. To decrease energy consumption, improve yields and mitigate environmental impacts, heterogeneous photocatalysis has emerged as a green and facile method, where its attractiveness is due to promises of providing low toxicity and low‐cost routes, driven by renewable energy. Among various semiconductor photocatalysts, bismuth‐based oxides are particularly promising candidates due to their high chemical and thermal stability, environmental friendliness, and good visible light responses. This paper provides a comprehensive overview of bismuth‐based oxide photocatalysts as employed in selective organic synthesis, including reaction mechanisms, with a particular focus on the reactive oxygen species involved. In addition, detailed information on the bismuth‐based oxide materials used as photocatalysts is covered. This includes crystal and electronic structures, strategies for improving photocatalytic performance, and a comparison of photocatalytic performances for key organic reactions. Furthermore, prospects and challenges of bismuth‐based oxide photocatalysts in selective organic synthesis are discussed, to aid future developments of efficient photocatalytic materials.

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