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dc.contributor.advisorJenekhe, Samson Aen_US
dc.contributor.authorHwang, Ye-Jinen_US
dc.date.accessioned2015-09-29T17:59:20Z
dc.date.submitted2015en_US
dc.identifier.otherHwang_washington_0250E_14518.pdfen_US
dc.identifier.urihttp://hdl.handle.net/1773/33646
dc.descriptionThesis (Ph.D.)--University of Washington, 2015en_US
dc.description.abstractThere has been tremendous progress in the development of conjugated polymer semiconductors in the last two decades for diverse applications in organic electronics and photonics. Most notably, advances in p-type (hole-conducting) polymers have enabled the development of high-performance organic field-effect transistors (OFETs) as well as more efficient fullerene-based organic photovoltaics (OPVs). In contrast, n-type (electron-conducting) polymer semiconductors remain relatively scarce and consequently the performance of n-channel OFETs and all-polymer solar cells has lagged far behind p-channel OFETs and fullerene-based OPVs. This dissertation mainly focuses on the design and synthesis of new n-type polymer semiconductors for device applications in n-channel OFETs and non-fullerene OPVs. It aims to achieve better understanding of the relationships between molecular structure, processing, morphology, and device performance. New n-type polymer semiconductors were developed based on strong electron withdrawing naphthalene diimide (NDI) building block with various selenophene derivatives as co-monomers. The resulting highly crystalline poly(naphthalene diimide)s (PNDIs) gave the electron mobility as high as 0.24 cm2/Vs in n-channel OFET measurements in air which is comparable or even higher mobility compared to most of the p-channel transistors. Using NDI-selenophene copolymer, PNDIS-HD, as acceptor, a photovoltaic performance with a power conversion efficiency (PCE) of 3.3 % (Jsc = 7.78 mA/cm2, Voc = 0.76 V, FF = 0.55) was achieved in all-polymer solar cells, and this work has stimulated a lot of current interest in fullerene-free OPVs. In further studies in all-polymer solar cells, highly enhanced photovoltaic performance was achieved by chemical modifications of acceptor polymers and controlling self-organization kinetics of polymer/polymer blend films. From these studies, a critical role of the bulk crystallinity of acceptor polymer was revealed, and provided an important criterion for the molecular design of high performance polymer acceptors. Furthermore, all-polymer solar cells with more favorable bulk morphology by slow self-organization of polymers facilitated by room temperature film aging resulted in enhanced charge carrier mobility and photocurrent. Resulting all-polymer solar cells with PCE over 7 % showed a great potential of non-fullerene solar cells and demonstrated for the first time a viable alternative pathway to organic photovoltaics.en_US
dc.format.mimetypeapplication/pdfen_US
dc.language.isoen_USen_US
dc.rightsCopyright is held by the individual authors.en_US
dc.subject.otherChemical engineeringen_US
dc.subject.otherchemical engineeringen_US
dc.titleMolecular Engineering of Polymer Semiconductors for Electronics and Photonicsen_US
dc.typeThesisen_US
dc.embargo.termsRestrict to UW for 1 year -- then make Open Accessen_US
dc.embargo.lift2016-09-28T17:59:20Z


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