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Title: Enhancing Photovoltaic Performance Using an All-Conjugated Random Copolymer to Tailor Bulk and Interfacial Morphology of the P3HT:ICBA Active Layer

Authors:
 [1];  [2];  [1];  [3];  [3];  [4]
  1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor MI 48109 USA
  2. Applied Physics Program, University of Michigan, Ann Arbor MI 48109 USA
  3. Department of Chemistry, University of Michigan, Ann Arbor MI 48109 USA
  4. Department of Materials Science and Engineering, University of Michigan, Ann Arbor MI 48109 USA; Applied Physics Program, University of Michigan, Ann Arbor MI 48109 USA
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Solar and Thermal Energy Conversion (CSTEC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1384128
DOE Contract Number:
SC0000957
Resource Type:
Journal Article
Resource Relation:
Journal Name: Advanced Functional Materials; Journal Volume: 24; Journal Issue: 35; Related Information: CSTEC partners with University of Michigan (lead); Kent State University
Country of Publication:
United States
Language:
English
Subject:
solar (photovoltaic), solar (thermal), phonons, thermal conductivity, thermoelectric, electrodes - solar, defects, charge transport, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Li, Anton, Amonoo, Jojo, Huang, Bingyuan, Goldberg, Peter K., McNeil, Anne J., and Green, Peter F. Enhancing Photovoltaic Performance Using an All-Conjugated Random Copolymer to Tailor Bulk and Interfacial Morphology of the P3HT:ICBA Active Layer. United States: N. p., 2014. Web. doi:10.1002/adfm.201401058.
Li, Anton, Amonoo, Jojo, Huang, Bingyuan, Goldberg, Peter K., McNeil, Anne J., & Green, Peter F. Enhancing Photovoltaic Performance Using an All-Conjugated Random Copolymer to Tailor Bulk and Interfacial Morphology of the P3HT:ICBA Active Layer. United States. doi:10.1002/adfm.201401058.
Li, Anton, Amonoo, Jojo, Huang, Bingyuan, Goldberg, Peter K., McNeil, Anne J., and Green, Peter F. Mon . "Enhancing Photovoltaic Performance Using an All-Conjugated Random Copolymer to Tailor Bulk and Interfacial Morphology of the P3HT:ICBA Active Layer". United States. doi:10.1002/adfm.201401058.
@article{osti_1384128,
title = {Enhancing Photovoltaic Performance Using an All-Conjugated Random Copolymer to Tailor Bulk and Interfacial Morphology of the P3HT:ICBA Active Layer},
author = {Li, Anton and Amonoo, Jojo and Huang, Bingyuan and Goldberg, Peter K. and McNeil, Anne J. and Green, Peter F.},
abstractNote = {},
doi = {10.1002/adfm.201401058},
journal = {Advanced Functional Materials},
number = 35,
volume = 24,
place = {United States},
year = {Mon Jul 14 00:00:00 EDT 2014},
month = {Mon Jul 14 00:00:00 EDT 2014}
}
  • This paper investigates the structure of films spin-coated from blends of the semiconducting polymers poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly{2,6-[4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene]-alt-4,7(2,1,3-benzo­thiadiazole)} (PCPDTBT). Such blends are of potential use in all-polymer solar cells in which both the acceptor and the donor material generate excitons to contribute to the photocurrent. Prompted by threefold performance gains seen in polymer/fullerene and polymer blend solar cells upon addition of pristine graphene, devices are prepared from P3HT/PCPDTBT blends both with and without graphene. This report focuses on the morphology of the active layer since this is of critical importance in determining performance. Small-angle neutron scattering (SANS) is utilized tomore » study this polymer blend with deuterated P3HT to provide contrast and permit the investigation of buried structure in neat and graphene-doped films. SANS reveals the presence of P3HT crystallites dispersed in an amorphous blend matrix of P3HT and PCPDTBT. The crystallites are approximately disc shaped and do not show any evidence of higher-order structure or aggregation. While the structure of the films does not change with the addition of graphene, there is a perceptible effect on the electronic properties and energy conversion efficiency in solar cells made from such films. Finally, determination of the active layer morphology yields crucial insight into structure–property relationships in organic photovoltaic devices.« less
  • The electronic properties of organic semiconductors are strongly influenced by intermolecular packing. When cast as thin films, crystalline π-conjugated molecules are strongly textured, potentially leading to anisotropic charge transport. Consequently, it is hypothesized that the orientation of crystallites in the active layer plays an important role in charge extraction and organic photovoltaic device performance. Here we demonstrate orientation control of molecular packing from mostly face-on to edge-on configurations in the active layer of P3HT- b-PFTBT block copolymer photovoltaics using 1-chloronaphthalene as a solvent additive. The effect of molecular orientations in P3HT crystals on charge transport and solar cell performance ismore » examined. We find that optimized photovoltaic device performance is independent of the crystalline texture of P3HT. Our observations provide further insights into the molecular organization required for efficient charge transport and overall device efficiencies. That is, the dominant crystal orientation, whether face-on or edge-on, is not critical to organic solar cells. Furthermore, a broad distribution of crystallite orientations ensures pathways for charge transport in any direction and enables efficient charge extraction in photovoltaic devices.« less
  • We demonstrated that the addition of block copolymers to binary donor–acceptor blends represents an effective approach to target equilibrium, co-continuous morphologies of interpenetrating donors and acceptors in our recent study. We report a study of the impact of all-conjugated poly(thieno[3,4-b]-thiophene-co-benzodithiophene)-b-polynaphthalene diimide (PTB7-b-PNDI) block copolymer additives on the electronic properties and photovoltaic performance of bulk heterojunction organic photovoltaic active layers comprised of a PTB7 donor and a phenyl-C61-butyric acid methyl ester (PCBM61) acceptor. We find that small amounts of BCP additives lead to improved performance due to a large increase in the device open-circuit voltage (VOC), and the VOC is pinnedmore » to this higher value for higher BCP additive loadings. Such results contrast prior studies of ternary blend OPVs where either a continuous change in VOC or a value of VOC pinned to the lowest value is observed. We hypothesize and provide evidence in the form of device and morphology analyses that the impact of VOC is likely due to the formation of a parallel bulk heterojunction made up of isolated PCBM and PNDI acceptor domains separated by intermediate PTB7 donor domains. Our work demonstrates that all-conjugated block copolymers can be utilized as additives to both dictate morphology and modulate the electronic properties of the active layer.« less