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dc.contributor.advisorPatil, Satish
dc.contributor.authorKrishnapriya, K C
dc.date.accessioned2022-05-18T10:14:45Z
dc.date.available2022-05-18T10:14:45Z
dc.date.submitted2021
dc.identifier.urihttps://etd.iisc.ac.in/handle/2005/5735
dc.description.abstractSinglet exciton fission (SEF) is the transformation of a photoexcited singlet exciton into two triplets localized on two chromophores coupled together. This process therefore produces two triplet excitons at the expense of one photon and hence can potentially improve the solar cell efficiency. An investigation into the excited state dynamics of three potential SEF candidates, pentacene dimers linked via diketopyrrolopyrrole derivative bridges, elucidates the significance of electronic spin density distribution in facilitating efficient intramolecular SEF (iSEF) in π-bridged pentacene dimers. Based on transient absorption spectroscopy measurements, efficient iSEF was only observed for the phenyl-derivative as only the phenyl-DPP bridge localizes α- and β-spin densities on distinct terminal pentacenes. Upon photoexcitation, a spin exchange mechanism enables iSEF from a singlet state which has an innate triplet pair character. An extraordinary correlation between the energy of excitation and SEF dynamics has been observed. The triplet absorption feature evolving as well as decaying at slower rate with decreasing energy of excitation was studied using transient absorption and photoluminescence measurements. This color sensitivity and origin of longer lived triplet species generated upon higher energy photoexcitation are analyzed to form a photophysical model. This contribution discourses the possibility multiple mechanistic pathways possible for an intramolecular dimer system to undergo SEF. In an attempt to experimentally analyze the practical challenges of increasing biradicaloid character of small molecules, a series of dicyanomethylated diketopyrrolopyrrole derivatives and their exciton dynamics was explored. For the most conjugated molecule SEF like features are observed in the fs TA of thin film which needs to be further investigated.en_US
dc.language.isoen_USen_US
dc.rightsI grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertationen_US
dc.subjectSinglet exciton fissionen_US
dc.subjectphotoexcitationen_US
dc.subjectphenyl-derivativeen_US
dc.subject.classificationResearch Subject Categories::NATURAL SCIENCES::Chemistryen_US
dc.titleRole of spin density and interchromophoric coupling in singlet fissionen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.grantorIndian Institute of Scienceen_US
dc.degree.disciplineFaculty of Scienceen_US


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