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1. SnF ₂ ‐Doped Cs ₂ SnI ₆ Ordered Vacancy Double Perovskite for Photovoltaic Applications

   https://doi.org/10.1002/solr.202300165  

   Murshed, Rubaiya; Thornton, Sarah; Walkons, Curtis; Koh, Jung Jae; Bansal, Shubhra (August 2023, Solar RRL)

   Air‐stable p‐type SnF₂:Cs₂SnI₆with a bandgap of 1.6 eV has been demonstrated as a promising material for Pb‐free halide perovskite solar cells. Crystalline Cs₂SnI₆phase is obtained with CsI, SnI₂, and SnF₂salts in gamma‐butyrolactone solvent, but not with dimethyl sulfoxide andN,N‐dimethylformamide solvents. Cs₂SnI₆is found to be stable for at least 1000 h at 100 °C when dark annealed in nitrogen atmosphere. In this study, Cs₂SnI₆has been used in a superstrate n–i–p planar device structure enabled by a spin‐coated absorber thickness of ≈2 μm on a chemical bath deposited Zn(O,S) electron transport layer. The best device power conversion efficiency reported here is 5.18% withV_OCof 0.81 V, 9.28 mA cm⁻²J_SC, and 68% fill factor. The dark saturation current and diode ideality factor are estimated as 1.5 × 10⁻³ mA cm⁻²and 2.18, respectively. The devices exhibit a highV_OCdeficit and low short‐circuit current density due to high bulk and interface recombination. Device efficiency can be expected to increase with improvement in material and interface quality, charge transport, and device engineering. 

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2. CsPbBr ₃ Perovskite Nanocrystals for Photocatalytic [3+2] Cycloaddition

   https://doi.org/10.1002/cssc.202301060  

   Lin, Yixiong; Yan, Yong (January 2024, ChemSusChem)

   Abstract Visible‐light‐induced halide‐exchange between halide perovskite and organohalide solvents has been studied in which photoinduced electron transfer from CsPbBr₃nanocrystals (NCs) to dihalomethane solvent molecules produces halide anions via reductive dissociation, followed by a spontaneous anion‐exchange. Photogenerated holes in this process are less focused. Here, for CsPbBr₃in dibromomethane (DBM), we discover that Br radical (Br⋅) is a key intermediate resulting from the hole oxidation. We successfully trapped Br⋅ with reported methods and found that Br⋅ is continuously generated in DBM under visible light irradiation, hence imperative for catalytic reaction design. Continuous Br⋅ formation within this halide‐exchange process is active for photocatalytic [3+2] cycloaddition for vinylcyclopentane synthesis, a privileged scaffold in medicinal chemistry, with good yield and rationalized diastereoselectivity. The NC photocatalyst is highly recyclable due to Br‐based self‐healing, leading to a particularly economic and neat heterogeneous reaction where the solvent DBM also acts as a co‐catalyst in perovskite photocatalysis. Halide perovskites, notable for efficient solar energy conversion, are demonstrated as exceptional photocatalysts for Br radical‐mediated [3+2] cycloaddition. We envisage such perovskite‐induced Br radical strategy may serve as a powerful chemical tool for developing valuable halogen radical‐involved reactions. 

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3. Perovskite Photocatalytic CO ₂ Reduction or Photoredox Organic Transformation?

   https://doi.org/10.1002/anie.202205572  

   San Martin, Jovan; Dang, Nhu; Raulerson, Emily; Beard, Matthew C.; Hartenberger, Joseph; Yan, Yong (August 2022, Angewandte Chemie International Edition)

   Abstract Metal‐halide perovskites have been explored as photocatalysts for CO₂reduction. We report that perovskite photocatalytic CO₂reduction in organic solvents is likely problematic. Instead, the detected products (i.e., CO) likely result from a photoredox organic transformation involving the solvent. Our observations have been validated using isotopic labeling experiments, band energy analysis, and new control experiments. We designed a typical perovskite photocatalytic setup in organic solvents that led to CO production of up to ≈1000 μmol g⁻¹ h⁻¹. CO₂reduction in organic solvents must be studied with extra care because photoredox organic transformations can produce orders of magnitude higher rate of CO or CH₄than is typical for CO₂reduction routes. Though CO₂reduction is not likely to occur, in situ CO generation is extremely fast. Hence a suitable system can be established for challenging organic reactions that use CO as a feedstock but exploit the solvent as a CO surrogate. 

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4. Hybrid Double Perovskite Containing Helium: [He ₂ ][CaZr]F ₆

   https://doi.org/10.1021/acs.chemmater.0c04782  

   Lloyd, Anthony J.; Hester, Brett R.; Baxter, Samuel J.; Ma, Shangye; Prakapenka, Vitali B.; Tkachev, Sergey N.; Park, Changyong; Wilkinson, Angus P. (April 2021, Chemistry of Materials)

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5. Spin reorientation in antiferromagnetic Dy ₂ FeCoO ₆ double perovskite

   https://doi.org/10.1088/1361-648X/abaeaa  

   Haripriya, G R; Heitmann, T W; Yadav, D K; Kaphle, G C; Ghimire, Madhav Prasad; Pradheesh, R; Joshi, J; Vora, P; Sethupathi, K; Sankaranarayanan, V; et al (January 2021, Journal of Physics: Condensed Matter)

   null (Ed.)