Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

Handle URI:
http://hdl.handle.net/10754/596174
Title:
Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells
Authors:
Dimitrov, Stoichko; Schroeder, Bob; Nielsen, Christian; Bronstein, Hugo; Fei, Zhuping; McCulloch, Iain ( 0000-0002-6340-7217 ) ; Heeney, Martin; Durrant, James
Abstract:
The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law.
KAUST Department:
Solar and Photovoltaic Engineering Research Center (SPERC); Physical Sciences and Engineering (PSE) Division
Citation:
Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells 2016, 8 (1):14 Polymers
Publisher:
MDPI AG
Journal:
Polymers
Issue Date:
13-Jan-2016
DOI:
10.3390/polym8010014
Type:
Article
ISSN:
2073-4360
Additional Links:
http://www.mdpi.com/2073-4360/8/1/14
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Solar and Photovoltaic Engineering Research Center (SPERC)

Full metadata record

DC FieldValue Language
dc.contributor.authorDimitrov, Stoichkoen
dc.contributor.authorSchroeder, Boben
dc.contributor.authorNielsen, Christianen
dc.contributor.authorBronstein, Hugoen
dc.contributor.authorFei, Zhupingen
dc.contributor.authorMcCulloch, Iainen
dc.contributor.authorHeeney, Martinen
dc.contributor.authorDurrant, Jamesen
dc.date.accessioned2016-02-14T14:08:25Zen
dc.date.available2016-02-14T14:08:25Zen
dc.date.issued2016-01-13en
dc.identifier.citationSinglet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells 2016, 8 (1):14 Polymersen
dc.identifier.issn2073-4360en
dc.identifier.doi10.3390/polym8010014en
dc.identifier.urihttp://hdl.handle.net/10754/596174en
dc.description.abstractThe lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law.en
dc.language.isoenen
dc.publisherMDPI AGen
dc.relation.urlhttp://www.mdpi.com/2073-4360/8/1/14en
dc.rightsThis is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.en
dc.subjectexcited statesen
dc.subjectdiffusionen
dc.subjectenergy gap lawen
dc.subjectnon-radiativeen
dc.subjectultrafast transient absorption spectroscopyen
dc.titleSinglet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cellsen
dc.typeArticleen
dc.contributor.departmentSolar and Photovoltaic Engineering Research Center (SPERC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalPolymersen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionCentre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, UKen
dc.contributor.institutionDepartment of Chemical Engineering, Stanford University, Stanford, CA 94305, USAen
dc.contributor.institutionDepartment of Chemistry, University College London, London WC1H 0AJ, UKen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorMcCulloch, Iainen
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.