Evidence for Interfacial Halogen Bonding

Swords, Wesley B.; Simon, Sarah J.; Parlane, Fraser G. L.; Dean, Rebecca K.; Kellett, Cameron W.; Hu, Ke; Meyer, Gerald J.; Berlinguette, Curtis P.

doi:10.1002/ange.201510641

Cited by 14 publications

(12 citation statements)

References 46 publications

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“…This holds true for cases such as halogen bonding, which has previously been reported as a strategy for maintaining high interfacial mediator concentrations. 24,25 However, the Coulombic effects discovered herein are of a much greater magnitude.…”

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confidence: 83%

Rapid Static Sensitizer Regeneration Enabled by Ion Pairing

et al. 2017

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An anionic Co complex, [Co(TTT) (NCS)] (TTT = 4,4',4″-tri-tert-butyl-2,2':6',2″-terpyridine and NCS = isothiocyanate), was synthesized for use in dye-sensitized solar cells (DSSCs). The Co complex was found to ion-pair with the hexacationic sensitizer [Ru(tmam)(dcb)] (tmam = 4,4'-bis(trimethylaminomethyl)-2,2'-bipyridine and dcb = 4,4'-(COH)-2,2'-bipyridine) anchored to TiO thin films immersed in acetonitrile solution. Visible light excitation of the ion pairs resulted in excited-state injection followed by rapid static regeneration of the oxidized sensitizer (<10 ns). The static component to regeneration gave an ion-pair equilibrium constant of 6000 M. This value is an order of magnitude smaller than the equilibrium constant determined for [Ru(tmam)(deeb)] (deeb = 4,4'-(COEt)-2,2'-bipyridine) dissolved in acetonitrile. DSSC studies employing [Co(TTT) (NCS)] or the cationic [Co(DTB)] (DTB = 4,4'-di-tert-butyl-2,2'-bipyridine) as redox mediators revealed a 3 fold photocurrent increase in the presence of the anionic cobalt complex. As the regeneration step was greatly enhanced through the formation of Coulombic ion pairs, both electron injection and regeneration were complete within 10 ns which is unprecedented for dye-sensitization. The results obtained reveal that ground-state ion-pairing can be a powerful strategy for DSSC optimization.

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Rapid Static Sensitizer Regeneration Enabled by Ion Pairing

et al. 2017

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“…Improvements in iodide oxidation at the power point are hence expected to result in higher DSSC efficiency. For this reason, sensitizers with high cationic charge, open coordination sites for iodide ligation, or halogen bonding functionalities have been designed to enhance the local iodide concentration at the TiO 2 interface through adduct formation between iodide and the sensitizer. − …”

Section: Introduction Background and Motivationmentioning

confidence: 99%

“…A family of four donor−π–acceptor sensitizers were synthesized for comparative halogen binding studies, Figure . − The carbon–halogen bond was positioned proximate to the triphenylamine donor which, after excited-state injection, was the expected site of halide oxidation.…”

Section: Introduction Background and Motivationmentioning

confidence: 99%

Halide Photoredox Chemistry

et al. 2019

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Halide photoredox chemistry is of both practical and fundamental interest. Practical applications have largely focused on solar energy conversion with hydrogen gas, through HX splitting, and electrical power generation, in regenerative photoelectrochemical and photovoltaic cells. On a more fundamental level, halide photoredox chemistry provides a unique means to generate and characterize one electron transfer chemistry that is intimately coupled with X−X bond-breaking and -forming reactivity. This review aims to deliver a background on the solution chemistry of I, Br, and Cl that enables readers to understand and utilize the most recent advances in halide photoredox chemistry research. These include reactions initiated through outer-sphere, halide-to-metal, and metal-toligand charge-transfer excited states. Kosower's salt, 1-methylpyridinium iodide, provides an early outer-sphere charge-transfer excited state that reports on solvent polarity. A plethora of new inner-sphere complexes based on transition and main group metal halide complexes that show promise for HX splitting are described. Long-lived charge-transfer excited states that undergo redox reactions with one or more halogen species are detailed. The review concludes with some key goals for future research that promise to direct the field of halide photoredox chemistry to even greater heights. CONTENTS 1. Introduction, Background, and Motivation

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“…Moreover, recently, the role of halogen bonding in increased dye regeneration rate was also established. 31 …”

Section: ■ Introductionmentioning

confidence: 99%

Unraveling the Dual Character of Sulfur Atoms on Sensitizers in Dye-Sensitized Solar Cells

Aghazada

Gao

Yella³

et al. 2016

ACS Appl. Mater. Interfaces

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Cyclometalated ruthenium sensitizers have been synthesized that differ with number of thiophene units on the auxiliary ligands. Sensitizers possessing four (SA25, SA246, and SA285) or none (SA282) sulfur atoms in their structures, were tested in solar cell devices employing I 3 − /I − redox mediator, enabling an estimation of the influence of sulfur− iodine/iodide interactions on dye-sensitized solar cell (DSC) performance. Power conversion efficiencies over 6% under simulated AM 1.5 illumination (1 Sun) were achieved with all the sensitizers. Consistently higher opencircuit voltage (V OC ) and fill factor (FF) values were measured using SA282. Scrutinizing the DSCs with these dyes by transient absorption spectroscopy (TAS) and electrochemical impedance spectroscopy (EIS) indicate that sulfur atom induced recombination cancels favorable increased regeneration resulting in decreased power conversion efficiencies (PCEs). The data indicate that, to reduce charge recombination channels, the use of sulfurcontaining aromatic rings should be avoided if possible in the dye structure when I 3 − /I − redox mediator is used.

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Evidence for Interfacial Halogen Bonding

Cited by 14 publications

References 46 publications

Rapid Static Sensitizer Regeneration Enabled by Ion Pairing

Rapid Static Sensitizer Regeneration Enabled by Ion Pairing

Halide Photoredox Chemistry

Unraveling the Dual Character of Sulfur Atoms on Sensitizers in Dye-Sensitized Solar Cells

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