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In the vast field of organic functional materials, viologens are widely recognized as an extremely versatile family of substances, due in part to the possibility of extending conjugation between the terminal pyridinium rings, for instance through the insertion of additional aromatic moieties. In this work, a new, extended viologen with a thiophene core and two acetylene bonds is presented. It was synthesized through a straightforward route, using well-established Sonogashira coupling reactions, and its optical properties were investigated by UV–visible absorption and fluorescence spectroscopy, revealing a very interesting material for diverse fluorescence-related applications. [ABSTRACT FROM AUTHOR]

A simple synthetic approach to BaZrS3, BaHfS3, and their solid solutions is presented and discussed here. The synthesis is performed under relatively mild conditions (T = 500°C) and is complete in a few hours. The reactants are powdered BaS, Me (Me: Zr, Hf) and S in a ratio 1:1:3, mixed and sealed under vacuum in borosilicate glass ampoules. No purification is usually required, and the yield is quantitative. The low synthesis temperature allows for the use of borosilicate glass as container material instead of silica glass, thus lowering the costs and simplifying the sealing of the reaction vessel; furthermore, the use of expensive ZrS2 and HfS2 is avoided. The same procedure was successfully used for the synthesis of solid solutions BaHf1‐xZrxS3 that were always obtained as crystalline single‐phase materials. The solid solutions display optical and structural properties that vary in a linear fashion with the composition and are intermediate between those of BaZrS3 and BaHfS3. The possibility of varying the band gap of the material between 1.78 (BaZrS3) and 2.11 eV (BaHfS3) in a continuous way by simply adjusting the Hf/Zr ratio is very intriguing for potential applications in multi‐junction and in‐door photovoltaic applications and light emitting devices. [ABSTRACT FROM AUTHOR]

Ba(Zr,Hf)S3 solid solutions are proposed for photovoltaic applications and a fast non-destructive measurement of the composition of these solutions and the identification of any possible secondary phases is a prerequisite for understanding their opto-electronic properties. Here we calculate the non-resonant one-phonon Raman spectra of pure BaHfS3 and BaZrS3, which show only subtle differences between them. To test this experimentally, a solution series of BaZr1-xHfxS3 (0≤x≤1) powders was synthesised and free of a secondary phase, HfS3 identified by 633 nm excitation Raman spectroscopy. The veracity of the synthesis method was confirmed by comparing X-ray diffractograms and optical absorption spectra of the BaZr0.5Hf0.5S3 solid solution to a 50:50 mixture of the pure ternary compounds. Experimental non-resonant Raman measurements on the solid solution powders confirm that only slight variations in the spectra are visible, making a solid solution composition determination difficult. However, exciting the solid solutions resonantly, leads to the appearance of new two-phonon modes in the Raman spectrum, which change significantly across the solid solution series. We consequently suggest that a rapid solid solution composition measurement can be made unambiguously by measuring the ratio of the intensities of the 825 cm-1 and 625 cm-1 Raman features., (© 2024 Wiley‐VCH GmbH.)

A new one-dimensional hybrid iodoplumbate, namely, 4,4'-(anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) lead iodide C 30 H 22 N 2 Pb 2 I 6 (AEPyPbI), is reported here for the first time with its complete characterization. The material exhibits remarkable thermal stability (up to 300 °C), and it is unreactive under ambient conditions toward water and atmospheric oxygen, due to the quaternary nature of the nitrogen atoms present in the organic cation. The cation exhibits strong visible fluorescence under ultraviolet (UV) irradiation, and when its iodide is combined with PbI 2 , it forms AEPyPb 2 I 6 , an efficient light-emitting material, with a photoluminescence emission intensity comparable to that of high-quality InP epilayers. The structure determination was obtained using three-dimensional electron diffraction, and the material was extensively studied by using a wide range of techniques, such as X-ray powder diffraction, diffuse reflectance UV-visible spectroscopy, thermogravimetry-differential thermal analysis, elemental analysis, Raman and infrared spectroscopies, and photoluminescence spectroscopy. The emissive properties of the material were correlated with its electronic structure by using state-of-the-art theoretical calculations. The complex, highly conjugated electronic structure of the cation interacts strongly with that of the Pb-I network, giving rise to the peculiar optoelectronic properties of AEPyPb 2 I 6 . The material, considering its relatively easy synthesis and stability, shows promise for light-emitting and photovoltaic devices. The use of highly conjugated quaternary ammonium cations may be useful for the development of new hybrid iodoplumbates and perovskites with optoelectronic properties tailored for specific applications., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

4,4'-(Anthracene-9,10-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) bismuth iodide (C 30 H 22 N 2 ) 3 Bi 4 I 18 (AEPyBiI) was obtained as a black powder by a very simple route by mixing an acetone solution of BiI 3 and an aqueous solution of C 30 H 22 N 2 I 2 . This novel perovskite is air and water stable and displays a remarkable thermal stability up to nearly 300 °C. The highly conjugated cation C 30 H 22 N 2 2+ is hydrolytically stable, being nitrogen atoms quaternarized, and this accounts for the insensitivity of the perovskite toward water and atmospheric oxygen under ambient conditions. The cation in aqueous solution is highly fluorescent under UV irradiation (emitting yellow-orange light). AEPyBiI as well is intensely luminescent, its photoluminescence emission being more than 1 order of magnitude greater than that of high-quality InP epilayers. The crystal structure of AEPyBiI was determined using synchrotron radiation single-crystal X-ray diffraction. AEPyBiI was extensively characterized using a wide range of techniques, such as X-ray powder diffraction, diffuse reflectance UV-vis spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopies, thermogravimetry-differential thermal analysis (TG-DTA), elemental analysis, electrospray ionization mass spectroscopy (ESI-MS), and photoluminescence spectroscopy. AEPyBiI displays a zero-dimensional (0D) perovskite structure in which the inorganic part is constituted by binuclear units consisting of two face-sharing BiI 6 octahedra (Bi 2 I 9 3- units). The C 30 H 22 N 2 2+ cations are stacked along the a -axis direction in a complex motif. Considering its noteworthy light-emitting properties coupled with an easy synthesis and environmental stability, and its composition that does not contain toxic lead or easily oxidable Sn(II), AEPyBiI is a promising candidate for environmentally friendly light-emitting devices., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)