Next Article in Journal
Cationic Nanocylinders Promote Angiogenic Activities of Endothelial Cells
Next Article in Special Issue
Organic Photovoltaics: More than Ever, an Interdisciplinary Field
Previous Article in Journal / Special Issue
Impact of Backbone Fluorination on π-Conjugated Polymers in Organic Photovoltaic Devices: A Review
Article Menu

Export Article

Open AccessFeature PaperArticle
Polymers 2016, 8(1), 14;

Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

Centre for Plastic Electronics, Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, UK
Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
Department of Chemistry, University College London, London WC1H 0AJ, UK
SPERC, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955–6900, Saudi Arabia
Author to whom correspondence should be addressed.
Academic Editor: Laure Biniek
Received: 16 November 2015 / Revised: 16 December 2015 / Accepted: 5 January 2016 / Published: 13 January 2016
(This article belongs to the Special Issue Organic Photovoltaics)
Full-Text   |   PDF [734 KB, uploaded 13 January 2016]   |  


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. View Full-Text
Keywords: excited states; diffusion; energy gap law; non-radiative; ultrafast transient absorption spectroscopy excited states; diffusion; energy gap law; non-radiative; ultrafast transient absorption spectroscopy

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

Dimitrov, S.D.; Schroeder, B.C.; Nielsen, C.B.; Bronstein, H.; Fei, Z.; McCulloch, I.; Heeney, M.; Durrant, J.R. Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells. Polymers 2016, 8, 14.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Polymers EISSN 2073-4360 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top