Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems

Handle URI:
http://hdl.handle.net/10754/621960
Title:
Ultrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systems
Authors:
Alsulami, Qana A. ( 0000-0001-5481-5414 )
Abstract:
The efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and photoinduced electron transfer dynamics is required to improve the device performance of solar cells. Here, we evaluated the effects of incorporating Pt(II) on intersystem crossing and photoinduced electron transfer by comparing and analyzing the photoexcited dynamics of DPP-Pt(II)(acac) and metal-free DPP with different acceptors such as TCNE, TMPyP, and TPyP.
Advisors:
Mohammed, Omar F. ( 0000-0001-8500-1130 )
Committee Member:
Bakr, Osman M. ( 0000-0002-3428-1002 ) ; Takanabe, Kazuhiro ( 0000-0001-5374-9451 ) ; Zhong, Dongping
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Chemical Sciences
Issue Date:
30-Nov-2016
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorMohammed, Omar F.en
dc.contributor.authorAlsulami, Qana A.en
dc.date.accessioned2016-12-07T07:39:35Z-
dc.date.available2016-12-07T07:39:35Z-
dc.date.issued2016-11-30-
dc.identifier.urihttp://hdl.handle.net/10754/621960-
dc.description.abstractThe efficiency of photoconversion systems, such as organic photovoltaic (OPV) cells, is largely controlled by a series of fundamental photophysical processes occurring at the interface before carrier collection. A profound understanding of ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) is the key determinant to improving the overall performances of photovoltaic devices. The discussion in this dissertation primarily focuses on the relevant parameters that are involved in photon absorption, exciton separation, carrier transport, carrier recombination and carrier collection in organic photovoltaic devices. A combination of steady-state and femtosecond broadband transient spectroscopies was used to investigate the photoinduced charge carrier dynamics in various donor-acceptor systems. Furthermore, this study was extended to investigate some important factors that influence charge transfer in donor-acceptor systems, such as the morphology, energy band alignment, electronic properties and chemical structure. Interestingly, clear correlations among the steady-state measurements, time-resolved spectroscopy results, grain alignment of the electron transporting layer (ETL), carrier mobility, and device performance are found. In this thesis, we explored the significant impacts of ultrafast charge separation and charge recombination at donor/acceptor (D/A) interfaces on the performance of a conjugated polymer PTB7-Th device with three fullerene acceptors: PC71BM, PC61BM and IC60BA. Time-resolved laser spectroscopy and high-resolution electron microscopy can illustrate the basis for fabricating solar cell devices with improved performances. In addition, we studied the effects of the incorporation of heavy metals into π-conjugated chromophores on electron transfer by monitoring the triplet state lifetime of the oligomer using transient absorption spectroscopy, as understanding the mechanisms controlling intersystem crossing and photoinduced electron transfer dynamics is required to improve the device performance of solar cells. Here, we evaluated the effects of incorporating Pt(II) on intersystem crossing and photoinduced electron transfer by comparing and analyzing the photoexcited dynamics of DPP-Pt(II)(acac) and metal-free DPP with different acceptors such as TCNE, TMPyP, and TPyP.en
dc.language.isoenen
dc.subjectCharge Transferen
dc.subjectCharge Separationen
dc.subjectfs-Transient Spectroscopyen
dc.subjectTime-Resolved Spectroscopyen
dc.subjectZnO grain alignmenten
dc.subjectphotoinduced electron transferen
dc.titleUltrafast Photoinduced Electron Transfer in Bimolecular Donor-Acceptor Systemsen
dc.typeDissertationen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberBakr, Osman M.en
dc.contributor.committeememberTakanabe, Kazuhiroen
dc.contributor.committeememberZhong, Dongpingen
thesis.degree.disciplineChemical Sciencesen
thesis.degree.nameDoctor of Philosophyen
dc.person.id128325en
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