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1. Dual-Sensitizer Photoanode for Bromide Oxidation

   https://doi.org/10.1021/acsaem.0c02544  

   Turlington, Michael D.; Brady, Matthew D.; Meyer, Gerald J. (January 2021, ACS Applied Energy Materials)

   null (Ed.)
2. Fluorescence Microscopy of Single Lead Bromide Nanocrystals Reveals Sharp Transitions during Their Transformation to Methylammonium Lead Bromide

   https://doi.org/10.1039/C8TC06470A  

   Yin, Bo; Cavin, John; Wang, Dong; Khan, Daniel; Shen, Meikun; Laing, Craig; Mishra, Rohan; Sadtler, Bryce (January 2019, Journal of Materials Chemistry C)

   Control over the nucleation and growth of lead-halide perovskite crystals is critical to obtain semiconductor films with high quantum yields in optoelectronic devices. In this report, we use the change in fluorescence brightness to image the transformation of individual lead bromide (PbBr 2 ) nanocrystals to methylammonium lead bromide (CH 3 NH 3 PbBr 3 ) via intercalation of CH 3 NH 3 Br. Analyzing this reaction one nanocrystal at a time reveals information that is masked when the fluorescence intensity is averaged over many particles. Sharp rises in the intensity of single nanocrystals indicate they transform much faster than the time it takes for the ensemble average to transform. While the ensemble reaction rate increases with increasing CH 3 NH 3 Br concentration, the intensity rises for individual nanocrystals are insensitive to the CH 3 NH 3 Br concentration. To explain these observations, we propose a phase-transformation model in which the reconstructive transitions necessary to convert a PbBr 2 nanocrystal into CH 3 NH 3 PbBr 3 initially create a high energy barrier for ion intercalation. A critical point in the transformation occurs when the crystal adopts the perovskite phase, at which point the activation energy for further ion intercalation becomes progressively smaller. Monte Carlo simulations that incorporate this change in activation barrier into the likelihood of reaction events reproduce key experimental observations for the intensity trajectories of individual particles. The insights gained from this study may be used to further control the crystallization of CH 3 NH 3 PbBr 3 and other solution-processed semiconductors. 

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3. “Soft” Alkali Bromide and Iodide Fluxes for Crystal Growth

   https://doi.org/10.3389/fchem.2020.00518  

   Klepov, Vladislav V.; Juillerat, Christian A.; Pace, Kristen A.; Morrison, Gregory; zur Loye, Hans-Conrad (June 2020, Frontiers in Chemistry)

   null (Ed.)
4. Bromide Causes Facet-Selective Atomic Addition in Gold Nanorod Syntheses

   https://doi.org/10.1021/acs.chemmater.0c01494  

   Brown, Micah; Wiley, Benjamin J. (January 2020, Chemistry of Materials)

   The aspect ratio-dependent properties of gold nanorods are used in a variety of applications, but the cause of anisotropic nanorod growth remains unclear. Measurements utilizing single-crystal electrodes were collected to determine what additive(s) in pentatwinned gold nanorod syntheses are responsible for facet-selective atomic addition. With cetyltrimethylammonium in the absence of bromide, the rate of atomic addition to Au(100) and Au(111) single crystals was the same, and isotropic nanoparticles were produced. The addition of increasing concentrations of bromide suppressed the rate of atomic addition to Au(100) relative to Au(111) and increased the aspect ratio of gold nanorods. Bromide was a more effective passivator of Au(100) in the absence of cetyltrimethylammonium, indicating cetyltrimethylammonium does not cause facet-selective atomic addition. Cetyltrimethylammonium surfactant is still necessary for gold nanorod growth because it reduces the rate of gold ion reduction and stabilizes suspended nanoparticles against aggregation. 

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5. 0D and 2D: The Cases of Phenylethylammonium Tin Bromide Hybrids

   https://doi.org/10.1021/acs.chemmater.0c01254  

   Xu, Liang-Jin; Lin, Haoran; Lee, Sujin; Zhou, Chenkun; Worku, Michael; Chaaban, Maya; He, Qingquan; Plaviak, Anna; Lin, Xinsong; Chen, Banghao; et al (June 2020, Chemistry of Materials)