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Self-Assembly and Its Impact on Interfacial Charge Transfer in Carbon Nanotube/P3HT Solar Cells

Bernardi, Marco and Giulianini, Michele and Grossman, Jeffrey C. (2010) Self-Assembly and Its Impact on Interfacial Charge Transfer in Carbon Nanotube/P3HT Solar Cells. ACS Nano, 4 (11). pp. 6599-6606. ISSN 1936-0851. doi:10.1021/nn1018297.

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Charge transfer at the interface of conjugated polymer and nanoscale inorganic acceptors is pivotal in determining the efficiency of excitonic solar cells. Despite intense efforts, carbon nanotube/polymer solar cells have resulted in disappointing efficiencies (<2%) due in large part to poor charge transfer at the interface. While the interfacial energy level alignment is clearly important, the self-assembly and the interface structure also play a major role in facilitating this charge transfer. To understand and control this effect to our advantage, we study the interface of commonly used conductive polymer poly-3-hexylthiophene (P3HT) and single-walled carbon nanotubes (SWNTs) with a combination of molecular dynamics simulations, absorption spectra experiments, and an analysis of charge transfer effects. Classical molecular dynamics simulations show that the P3HT wraps around the SWNTs in a number of different conformations, including helices, bundles, and more elongated conformations that maximize planar π−π stacking, in agreement with recent experimental observations. Snapshots from the MD simulations reveal that the carbon nanotubes play an important templating role of increasing the π-conjugation in the system, an effect deriving from the π−π stacking interaction at the interface and the 1-dimensional (1D) nature of the SWNTs, and independent of the SWNT chirality. We show how this increase in the system conjugation could largely improve the charge transfer in P3HT−SWNT type II heterojunctions and support our results with absorption spectra measurements of mixtures of carbon nanotubes and P3HT. These findings open possibilities for improved preparation of polymeric solar cells based on carbon nanotubes and on 1D nanomaterials in general.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Bernardi, Marco0000-0001-7289-9666
Grossman, Jeffrey C.0000-0003-1281-2359
Additional Information:© 2010 American Chemical Society. Received for review July 29, 2010 and accepted October 18, 2010. Publication Date (Web): October 28, 2010. M.G. is thankful to N. Motta and J. M. Bell for support and discussion. M.G. also acknowledges support from the Queensland Government through the NIRAP project “Solar Powered Nanosensors” and ARCNN for the 2009 Travel Fellowship Grant. Note Added After ASAP Publication: This article was published on October 28, 2010. Figure caption and related text for Figure 1 have been corrected; an Acknowledgment has also been added. The corrected version was reposted November 23, 2010. Supporting Information: Details of the MD simulations and computational procedures; videos of a number of simulation runs of P3HT and SWNTs; preparation and experimental setup for the optical absorption measurements; additional optical spectra; discussion and estimate of the impact of the conjugation length on the interface charge transfer.
Funding AgencyGrant Number
Queensland GovernmentUNSPECIFIED
Australian Research Council Nanotechnology Network (ARCNN)UNSPECIFIED
Subject Keywords:self-assembly; organic photovoltaics; excitonic solar cells; bulk heterojunction; P3HT; conjugation length; carbon nanotube; molecular dynamics; charge transfer
Issue or Number:11
Record Number:CaltechAUTHORS:20150923-135830701
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Official Citation:Self-Assembly and Its Impact on Interfacial Charge Transfer in Carbon Nanotube/P3HT Solar Cells Marco Bernardi, Michele Giulianini, and Jeffrey C. Grossman ACS Nano 2010 4 (11), 6599-6606 DOI: 10.1021/nn1018297
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60446
Deposited By: George Porter
Deposited On:23 Sep 2015 22:10
Last Modified:10 Nov 2021 22:34

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