Intercalated vs nonintercalated morphologies in donor-acceptor bulk heterojunction solar cells: PBTTT: fullerene charge generation and recombination revisited

Collado-Fregoso, Elisa, Hood, Samantha N., Shoaee, Safa, Schroeder, Bob C., McCulloch, Iain, Kassal, Ivan, Neher, Dieter and Durrant, James R. (2017) Intercalated vs nonintercalated morphologies in donor-acceptor bulk heterojunction solar cells: PBTTT: fullerene charge generation and recombination revisited. The Journal of Physical Chemistry Letters, 8 17: 4061-4068. doi:10.1021/acs.jpclett.7b01571


Author Collado-Fregoso, Elisa
Hood, Samantha N.
Shoaee, Safa
Schroeder, Bob C.
McCulloch, Iain
Kassal, Ivan
Neher, Dieter
Durrant, James R.
Title Intercalated vs nonintercalated morphologies in donor-acceptor bulk heterojunction solar cells: PBTTT: fullerene charge generation and recombination revisited
Journal name The Journal of Physical Chemistry Letters   Check publisher's open access policy
ISSN 1948-7185
Publication date 2017-09-01
Sub-type Article (original research)
DOI 10.1021/acs.jpclett.7b01571
Open Access Status Not yet assessed
Volume 8
Issue 17
Start page 4061
End page 4068
Total pages 8
Publisher American Chemical Society
Language eng
Abstract In this Letter, we study the role of the donor:acceptor interface nanostructure upon charge separation and recombination in organic photovoltaic devices and blend films, using mixtures of PBTTT and two different fullerene derivatives (PC70BM and ICTA) as models for intercalated and nonintercalated morphologies, respectively. Thermodynamic simulations show that while the completely intercalated system exhibits a large free-energy barrier for charge separation, this barrier is significantly lower in the nonintercalated system and almost vanishes when energetic disorder is included in the model. Despite these differences, both femtosecond-resolved transient absorption spectroscopy (TAS) and time-delayed collection field (TDCF) exhibit extensive first-order losses in both systems, suggesting that geminate pairs are the primary product of photoexcitation. In contrast, the system that comprises a combination of fully intercalated polymer:fullerene areas and fullerene-aggregated domains (1:4 PBTTT:PC70BM) is the only one that shows slow, second-order recombination of free charges, resulting in devices with an overall higher short-circuit current and fill factor. This study therefore provides a novel consideration of the role of the interfacial nanostructure and the nature of bound charges and their impact upon charge generation and recombination.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
HERDC Pre-Audit
 
Versions
Version Filter Type
Citation counts: Scopus Citation Count Cited 2 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 26 Sep 2017, 00:15:25 EST by Web Cron on behalf of Learning and Research Services (UQ Library)