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Title: Correlating highpower conversion efficiency of PTB7:PC 71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC 71BM inverted organic solar cells]

Advances in materials design and device engineering led to inverted organic solar cells (i-OSCs) with superior power conversion efficiencies (PCEs) to their conventional counterparts, in addition to the well-known better ambient stability. Despite the significant progress, however, it has so far been unclear how the morphologies of the photoactive layer and its interface with the cathode modifying layer impact device performance. Here, we report an in-depth morphology study of the i-OSC active and cathode modifying layers, employing a model system with the well-established bulk-heterojunction, PTB7:PC 71BM as the active layer and poly-[(9,9-bis(3 -( N,N-dimethylamino)propyl)-2,7-fluorene)- alt-2,7-(9,9-dioctylfluorene)] (PFN) as the cathode surface modifying layer. We have also identified the role of a processing additive, 1,8-diiodooctane (DIO), used in the spin-casting of the active layer to increase PCE. Using a variety of characterization techniques, we demonstrate that the high PCEs of i-OSCs are due to the smearing (diffusion) of electron-accepting PC 71BM into the PFN layer, resulting in improved electron transport. The PC 71BM diffusion occurs after spin-casting the active layer onto the PFN layer, when residual solvent molecules act as a plasticizer. Furthermore, the DIO additive, with a higher boiling point than the host solvent, has a longer residence time in themore » spin-cast active layer, resulting in more PC 71BM smearing and therefore more efficient electron transport. This work provides important insight and guidance to further enhancement of i-OSC performance by materials and interface engineering.« less
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2]
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nanoscale
Additional Journal Information:
Journal Volume: 7; Journal Issue: 38; Journal ID: ISSN 2040-3364
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; inverted solar cell; neutron reflectivity; SANS; 36 MATERIALS SCIENCE
OSTI Identifier:
1222555
Alternate Identifier(s):
OSTI ID: 1352519

Das, Sanjib, Browning, Jim, Gu, Gong, Yang, Bin, Do, Changwoo, Chen, Wei, Chen, Jihua, Ivanov, Ilia N, Hong, Kunlun, Rondinone, Adam J., Joshi, Pooran C., Geohegan, David B., Xiao, Kai, and Keum, Jong K.. Correlating highpower conversion efficiency of PTB7:PC71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC71BM inverted organic solar cells]. United States: N. p., Web. doi:10.1039/c5nr03332b.
Das, Sanjib, Browning, Jim, Gu, Gong, Yang, Bin, Do, Changwoo, Chen, Wei, Chen, Jihua, Ivanov, Ilia N, Hong, Kunlun, Rondinone, Adam J., Joshi, Pooran C., Geohegan, David B., Xiao, Kai, & Keum, Jong K.. Correlating highpower conversion efficiency of PTB7:PC71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC71BM inverted organic solar cells]. United States. doi:10.1039/c5nr03332b.
Das, Sanjib, Browning, Jim, Gu, Gong, Yang, Bin, Do, Changwoo, Chen, Wei, Chen, Jihua, Ivanov, Ilia N, Hong, Kunlun, Rondinone, Adam J., Joshi, Pooran C., Geohegan, David B., Xiao, Kai, and Keum, Jong K.. 2015. "Correlating highpower conversion efficiency of PTB7:PC71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC71BM inverted organic solar cells]". United States. doi:10.1039/c5nr03332b. https://www.osti.gov/servlets/purl/1222555.
@article{osti_1222555,
title = {Correlating highpower conversion efficiency of PTB7:PC71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC71BM inverted organic solar cells]},
author = {Das, Sanjib and Browning, Jim and Gu, Gong and Yang, Bin and Do, Changwoo and Chen, Wei and Chen, Jihua and Ivanov, Ilia N and Hong, Kunlun and Rondinone, Adam J. and Joshi, Pooran C. and Geohegan, David B. and Xiao, Kai and Keum, Jong K.},
abstractNote = {Advances in materials design and device engineering led to inverted organic solar cells (i-OSCs) with superior power conversion efficiencies (PCEs) to their conventional counterparts, in addition to the well-known better ambient stability. Despite the significant progress, however, it has so far been unclear how the morphologies of the photoactive layer and its interface with the cathode modifying layer impact device performance. Here, we report an in-depth morphology study of the i-OSC active and cathode modifying layers, employing a model system with the well-established bulk-heterojunction, PTB7:PC71BM as the active layer and poly-[(9,9-bis(3 -(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) as the cathode surface modifying layer. We have also identified the role of a processing additive, 1,8-diiodooctane (DIO), used in the spin-casting of the active layer to increase PCE. Using a variety of characterization techniques, we demonstrate that the high PCEs of i-OSCs are due to the smearing (diffusion) of electron-accepting PC71BM into the PFN layer, resulting in improved electron transport. The PC71BM diffusion occurs after spin-casting the active layer onto the PFN layer, when residual solvent molecules act as a plasticizer. Furthermore, the DIO additive, with a higher boiling point than the host solvent, has a longer residence time in the spin-cast active layer, resulting in more PC71BM smearing and therefore more efficient electron transport. This work provides important insight and guidance to further enhancement of i-OSC performance by materials and interface engineering.},
doi = {10.1039/c5nr03332b},
journal = {Nanoscale},
number = 38,
volume = 7,
place = {United States},
year = {2015},
month = {7}
}

Works referenced in this record:

Air-stable inverted flexible polymer solar cells using zinc oxide nanoparticles as an electron selective layer
journal, June 2008
  • Hau, Steven K.; Yip, Hin-Lap; Baek, Nam Seob
  • Applied Physics Letters, Vol. 92, Issue 25, Article No. 253301
  • DOI: 10.1063/1.2945281

Thermally Stable, Efficient Polymer Solar Cells with Nanoscale Control of the Interpenetrating Network Morphology
journal, October 2005
  • Ma, W.; Yang, C.; Gong, X.
  • Advanced Functional Materials, Vol. 15, Issue 10, p. 1617-1622
  • DOI: 10.1002/adfm.200500211

Package-Free Flexible Organic Solar Cells with Graphene top Electrodes
journal, April 2013
  • Liu, Zhike; Li, Jinhua; Yan, Feng
  • Advanced Materials, Vol. 25, Issue 31, p. 4296-4301
  • DOI: 10.1002/adma.201205337

Independent Control of Bulk and Interfacial Morphologies of Small Molecular Weight Organic Heterojunction Solar Cells
journal, July 2012
  • Zimmerman, Jeramy D.; Xiao, Xin; Renshaw, Christopher Kyle
  • Nano Letters, Vol. 12, Issue 8, p. 4366-4371
  • DOI: 10.1021/nl302172w

Polymer solar cells with enhanced open-circuit voltage and efficiency
journal, November 2009
  • Chen, Hsiang-Yu; Hou, Jianhui; Zhang, Shaoqing
  • Nature Photonics, Vol. 3, Issue 11, p. 649-653
  • DOI: 10.1038/nphoton.2009.192

High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends
journal, October 2005
  • Li, Gang; Shrotriya, Vishal; Huang, Jinsong
  • Nature Materials, Vol. 4, Issue 11, p. 864-868
  • DOI: 10.1038/nmat1500

For the Bright Future-Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%
journal, May 2010
  • Liang, Yongye; Xu, Zheng; Xia, Jiangbin
  • Advanced Materials, Vol. 22, Issue 20, p. E135-E138
  • DOI: 10.1002/adma.200903528

The Role of Mesoscopic PCBM Crystallites in Solvent Vapor Annealed Copolymer Solar Cells
journal, February 2009
  • Bull, Tricia A.; Pingree, Liam S. C.; Jenekhe, Samson A.
  • ACS Nano, Vol. 3, Issue 3, p. 627-636
  • DOI: 10.1021/nn800878c