Surface engineered angstrom thick ZnO-sheathed TiO2 nanowires as photoanodes for performance enhanced dye-sensitized solar cells

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buir.contributor.authorOkyay, Ali Kemal
dc.citation.epage16876en_US
dc.citation.issueNumber40en_US
dc.citation.spage16867en_US
dc.citation.volumeNumber2en_US
dc.contributor.authorUlusoy, T. G.en_US
dc.contributor.authorGhobadi, A.en_US
dc.contributor.authorOkyay, Ali Kemalen_US
dc.date.accessioned2015-07-28T12:02:51Z
dc.date.available2015-07-28T12:02:51Z
dc.date.issued2014en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.departmentNanotechnology Research Center (NANOTAM)en_US
dc.departmentInstitute of Materials Science and Nanotechnology (UNAM)en_US
dc.description.abstractThis paper presents a systematic study on the effects of angstrom-thick atomic layer deposited (ALD) ZnO sheaths on hydrothermally-grown TiO2 nanowires (NWs) used as photoanodes in dye-sensitized solar cells (DSSCs). We designed, synthesized and characterized the samples prepared using different numbers of ZnO cycles and compared their photovoltaic (PV) performances. The device consisting of TiO2 NWs coated with the optimum thickness (two cycles) of ZnO shell exhibits a three-fold increase in efficiency compared to a control reference device. This paper reports results and features that demonstrate the passivation of surface state traps upon deposition of ZnO shells. While this passivation of surface traps provides a reduction in the back-reactions of the surface state mediated electrons (KET trap), it is speculated that ZnO-induced surface band bending (SBB) substantially reduces the recombination rate of the device by reducing the recombination rate of the conduction band (CB) electrons (KET CB). Moreover, an enhancement in the amount of dye uptake for ZnO-coated TiO2 samples is observed and explained with the isoelectric point (IEP) concept. In spite of the excellent PV power conversion efficiencies achieved by the first ZnO cycles, thicker layers impede the electron injection rate, reducing the efficiency of the device by capturing the photogenerated dye electrons in ZnO quantum wells. Here, we investigate the mechanisms contributing to this unprecedented change and correlate them with the enhancement in device efficiency.en_US
dc.description.provenanceMade available in DSpace on 2015-07-28T12:02:51Z (GMT). No. of bitstreams: 1 8367.pdf: 1445299 bytes, checksum: 7c375f43d85e4bc7c58e55e348020717 (MD5)en
dc.identifier.doi10.1039/C4TA03445Gen_US
dc.identifier.issn2050-7488
dc.identifier.urihttp://hdl.handle.net/11693/12753
dc.language.isoEnglishen_US
dc.publisherRoyal Society of Chemistryen_US
dc.relation.isversionofhttps://doi.org/10.1039/C4TA03445Gen_US
dc.source.titleJournal of Materials Chemistry Aen_US
dc.subjectAtomic Layer Depositionen_US
dc.subjectDye-sensitized Solar Cellsen_US
dc.subjectEfficiencyen_US
dc.subjectElectronsen_US
dc.subjectNanowiresen_US
dc.subjectPassivationen_US
dc.subjectSurface Reactionsen_US
dc.subjectSurface Statesen_US
dc.subjectTitanium Dioxideen_US
dc.subjectZinc Oxideen_US
dc.titleSurface engineered angstrom thick ZnO-sheathed TiO2 nanowires as photoanodes for performance enhanced dye-sensitized solar cellsen_US
dc.typeArticleen_US

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Department of Electrical and Electronics Engineering
Institute of Materials Science and Nanotechnology (UNAM)
Nanotechnology Research Center (NANOTAM)