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Vladimir Bulović. Chang, Wendi Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science 2013-11-18T19:15:18Z 2013-11-18T19:15:18Z 2013 2013 http://hdl.handle.net/1721.1/82374 862074706 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013. Cataloged from PDF version of thesis. Includes bibliographical references (p. 63-65). This thesis proposes and demonstrates a pressure probing technique for studying the effects of local dielectric changes on the excitonic energy levels in amorphous organic thin films for optoelectronic device applications. Compression of organic films causes a decrease in intermolecular spacing and, through solvation effects, lowers the exciton transition energy. A series of steady-state photoluminescence (PL) measurements performed on doped organic thin films demonstrated the applicability of pressure probing in measuring solvation effects, and fitted to solvation theory. Since a pressure probing technique eliminates composition differences and sample-to-sample variability, in comparison with doping methods, it may be a simpler method of observing energy shifts in solvation effects. Further investigation into spectral diffusion for films under compression indicates a change in spectral diffusion rate due to change in molecular packing density. Comparisons were made between spectral diffusion rates for films under pressure and films of different doping concentrations. Initial measurements of pressure effects on exciplex charge-transfer states in bulk heterojunction films are performed to show change in emission lifetimes. This work could provide a better understanding of the singlet-triplet exciton coupling rates and have a significant impact on device optimization for organic light-emitting diodes (OLEDs) and solar cell applications. by Wendi Chang. S.M. 65 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Electrical Engineering and Computer Science. Characterization of Local field effect in organic film using pressure technique Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="2ef39a0f-2739-466d-a583-5e850c72342e"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Characterization of Local field effect in organic film using pressure technique</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2013</PublicationDate> <Authors> <Author> <DisplayName>Chang, Wendi</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Electrical Engineering and Computer Science.</Keyword> <Abstract>This thesis proposes and demonstrates a pressure probing technique for studying the effects of local dielectric changes on the excitonic energy levels in amorphous organic thin films for optoelectronic device applications. Compression of organic films causes a decrease in intermolecular spacing and, through solvation effects, lowers the exciton transition energy. A series of steady-state photoluminescence (PL) measurements performed on doped organic thin films demonstrated the applicability of pressure probing in measuring solvation effects, and fitted to solvation theory. Since a pressure probing technique eliminates composition differences and sample-to-sample variability, in comparison with doping methods, it may be a simpler method of observing energy shifts in solvation effects. Further investigation into spectral diffusion for films under compression indicates a change in spectral diffusion rate due to change in molecular packing density. Comparisons were made between spectral diffusion rates for films under pressure and films of different doping concentrations. Initial measurements of pressure effects on exciplex charge-transfer states in bulk heterojunction films are performed to show change in emission lifetimes. This work could provide a better understanding of the singlet-triplet exciton coupling rates and have a significant impact on device optimization for organic light-emitting diodes (OLEDs) and solar cell applications.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>