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Discerning Bulk and Interfacial Polarons in a Dual Electron Donor/Acceptor Polymer.

ABSTRACT: The active layer of organic solar cells typically possesses a complex morphology, with amorphous donor/acceptor mixed domains present in addition to purer, more crystalline domains. These crystalline domains may represent an energy sink for free charges that aids charge separation and suppresses bimolecular recombination. The first step in exploiting this behavior is the identification and characterization of charges located in these different domains. Herein, the generation and recombination of both bulk and interfacial polarons are demonstrated in the dual electron donor/acceptor polymer XIND using transient absorption spectroscopy. The absorption spectra of XIND bulk polarons, present in pristine polymer domains, are clearly distinguishable from those of polarons present at the donor/acceptor interface. Furthermore, it is shown that photogenerated polarons are transferred from the interface to the bulk. These findings support the energy sink hypothesis and offer a way to maximize morphology relationships to enhance charge generation and suppress recombination.

SUBMITTER: Marin-Beloqui JM

PROVIDER: S-EPMC6614788 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Discerning Bulk and Interfacial Polarons in a Dual Electron Donor/Acceptor Polymer.

Marin-Beloqui Jose M JM Fallon Kealan J KJ Bronstein Hugo H Clarke Tracey M TM

The journal of physical chemistry letters 20190625 13

The active layer of organic solar cells typically possesses a complex morphology, with amorphous donor/acceptor mixed domains present in addition to purer, more crystalline domains. These crystalline domains may represent an energy sink for free charges that aids charge separation and suppresses bimolecular recombination. The first step in exploiting this behavior is the identification and characterization of charges located in these different domains. Herein, the generation and recombination of ...[more]

PMID: 31244264

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Project description:Microbially-mediated uranium bioremediation has been demonstrated in uranium contaminated aquifers when acetate was artificially supplied and growth of the natural population of Geobacteraceae was stimulated. In order to mimic the environmental response to acetate, steady-state cells of G. sulfureducens were cultured in chemostats under conditions of either 1) acetate as the sole electron donor and limiting factor and fumarate as the sole electron acceptor or 2) acetate was supplied in excess with fumarate as sole electron acceptor and limiting factor. In silico fluxome modeling and transcriptome analysis were used as tools for investigating the cell response to the acetate availability. For global gene expression profiling, a DNA microarray of the complete G. sulfurreducens genome was used. Statistically significant results were obtained from two-color, dye swap hybridizations produced from a total of three biological replicates. Eight technical replicates were tested from two of the biological replicates and six technical replicates were tested from the third biological replicate. Major findings from this study are given as follows. The in silico model successfully predicted a higher TCA-cycle flux (ca. 2-fold) under acetate-excess conditions, suggesting that catabolism of acetate is favored with respect to anabolism, and thus more electrons are available for metal reduction. Transcriptome analyses offered a comprehensive picture of the regulation points subjected to the acetate availability. Under acetate-excess conditions, acetate transporters in the G. sulfurreducens genome were down-regulated. In addition the oxidation-related acetyl-CoA transferase was up-regulated approximately three-fold and the assimilatory-related acetate kinase was down-regulated approximately two-fold, respectively, indicating that the transcriptional regulation of acetate activation may be the key point for coping with the excess of acetate and increasing the TCA flux. The level of transcription for 10 c-type cytochromes was significantly increased in cells cultured with an excess of acetate. OmcS, an outer-membrane cytochrome which actively participates in electron transfer to Fe(III)-oxides and graphite electrodes from fuel cells, showed one of the highest fold increases in transcription. The integration of in silico modeling and genome-wide analysis shows for first time how G. sulffureducens adapts its metabolic flux and transcriptional network for optimizing the use of acetate as an electron donor for exocellular respiration instead of for use as a carbon source for biomass production. Keywords: Geobacter, gene expression, acetate limitation, fumarate limitation

Dataset Information

Discerning Bulk and Interfacial Polarons in a Dual Electron Donor/Acceptor Polymer.

Publications

Discerning Bulk and Interfacial Polarons in a Dual Electron Donor/Acceptor Polymer.

Similar Datasets

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