Redox Potentials using Pulse Radiolysis
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Transcript of Redox Potentials using Pulse Radiolysis
PowerPoint Presentation
Stephanie HernandezDr. Matthew BirdNick BonuraPlotting Relative Redox Potentials in THF without Electrolyte
Organic Photovoltaic Cells Advantages Organic polymers used in the cell are solution-processable, cheap, and in abundance supply Constructed utilizing Roll to Roll processing Applied to various substrates for a wider range of applications compared to silicon solar cells.Potential to retrofit buildings to supply a secondary power source.
Source: http://www.sigmaaldrich.com/materials-science/organic-electronics/opv-tutorial.html
2http://www.sigmaaldrich.com/materials-science/organic-electronics/opv-tutorial.htmlhttp://solarenergygroupe.com/
Source: http://www.sigmaaldrich.com/materials-science/organic-electronics/opv-tutorial.htmlOrganic Photovoltaic Cells
3http://www.sigmaaldrich.com/materials-science/organic-electronics/opv-tutorial.htmlhttp://solarenergygroupe.com/Challenges Low efficiencies reported compared to silicon solar cellsLack of understanding of charge separationExtending lifetime of devicesDifficulty estimating HOMO and LUMO levels of materials
4Purpose To avoid propagation uncertainties in results and further aid investigation into OPV devices by providing redox potentials of polymers and small molecules in THF without electrolyte.
ObjectivesDevelop a redox ladder using pulse radiolysis results from various donor-acceptor solutions in THF Test a fit function for the change in electron transfer equilibriumTest several polymers studies by the OPV community for redox values
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PCPDTBT[TBAPF6]
CoCp2 0/+
*Information on the reduction potentials in 0.1M [TBAPF6] in THF was taken from another experimentCreating the Ladderp-NBz
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[TBAPF6]
CoCp2 0/+p-NBzMy experiment: Fill in the redoxladder from 1,4-Dinitrobenzene (p-NBz) to the solvated electron.
Nicks experiment:Test the fit function against Cobaltocenium (CoCp2) and p-NBz, while determining the oxidation/reduction values. *Information on the reduction potentials in 0.1M [TBAPF6] in THF was taken from another experimentCreating the LadderPCPDTBT
6Effect of ion-pairing and ionic environment on reduction potential
Might be defined as formal potential in presence of salt
Methods70.5cmAcceptorDonorElectron pulseLight source
FilterDetector
The Experiment
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The Experiment
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Results 9
Results10
F8BTPhthalic Anhydride (PA)Nitrobenzene (NBz)IDTBT2-Ethyl-anthra quinone (EtAQ)Tetramethyl Benzoquinone (DQ) E(-)Pyromellitic Dianhydride (PMDA)We can start to expand our ladder by determining the Eredox between different compounds until we connect the ladder to 1,4-Dinitrobenzene and Nicks experiment.DonorAcceptorG (meV)F8BTPA69PANBz46NBzIDTBT50NBzEtAQ113EtAQDQ87DQPMDA145
Conclusions11This ladder is getting extensive but still requires more molecules and conjugate polymers to fill in gaps between p-NBz and the solvated electronThis method will help narrow down where a polymers reduction potential lies relative to other molecules in THF This will aid in rational designs of OPV cells as new combinations of donor an acceptor molecules are tested
Acknowledgements12This project was supported by the U.S. Department of Energy, Science Undergraduate Laboratory Internships Program (SULI). The author also thanks John Miller for his expertise and useful advice without whom this project would not have been possible. Thanks to Brookhaven National Laboratory and the Office of Educational Programs for hosting and granting access to the Laser Electron Accelerator Facility (LEAF)for this project.