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Title: Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells

In this work, we report improved performance by controlling morphology using different fullerene derivatives in poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b]dithiophene-alt-5,6-bis(dodecyloxy)-4,7- di(thieno[3,2-b]thiophen-2-yl)-benzo[c][1,2,5]thiadiazole} (PBDT-TBT-alkoBT) based organic solar cells. PC60BM and PC70BM fullerenes were used to investigate the characteristic change in morphology and device performance. Fullerene affects device efficiency by changing active layer morphology. PC70BM with broader absorption than PC 60BM resulted in reduced device performance which was elucidated by the intermixed granular morphology separating each larger grain in the PC70BM/polymer composite layer which created higher density of traps. However after adding additive 1,8-diiodooctane (DIO), the fibrous morphology was observed due to reduced solubility of polymer and increased solubility of PC 70BM in chloroform. The fibrous morphology improved charge transport leading to increase in overall device performance. Atomic force microscopies (AFM), photo induced charge extraction by linearly increasing voltage (photo-CELIV), and Kelvin prove force microscope (KPFM) were used to investigate nanoscale morphology of active layer with different fullerene derivatives. For PC 60BM based active layer, AFM images revealed dense fibrous morphology and more distinct fibrous morphology was observed by adding DIO. The PC 70BM based active layer only exhibited intermixed granular morphology instead of fibrous morphology observed in PC60BM based active layer. However, addition of DIO inmore » PC 70BM based active layer led to fibrous morphology. When additive DIO was not used, a wider distribution of surface potential was observed for PC 70BM than PC 60BM based active layer by KPFM measurements, indicating 2 polymer and fullerene domains are separated. When DIO was used, narrower distribution of surface potential for both PC 70BM and PC 60BM based active layers was observed. Photo-CELIV experiment showed larger extracted charge carrier density and mobility in PC 70BM/DIO film.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. South Dakota State Univ., Brookings, SD (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 3; Journal Issue: 29; Journal ID: ISSN 2050-7488
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY
OSTI Identifier:
1286906

Khatiwada, Devendra, Venkatesan, Swaminathan, Chen, QIliang, Chen, Jihua, Adhikari, Nirmal, Dubey, Ashish, Mitul, Abu Farzan, Mohammed, Lal, and Qiao, Qiquan. Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells. United States: N. p., Web. doi:10.1039/C5TA02709H.
Khatiwada, Devendra, Venkatesan, Swaminathan, Chen, QIliang, Chen, Jihua, Adhikari, Nirmal, Dubey, Ashish, Mitul, Abu Farzan, Mohammed, Lal, & Qiao, Qiquan. Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells. United States. doi:10.1039/C5TA02709H.
Khatiwada, Devendra, Venkatesan, Swaminathan, Chen, QIliang, Chen, Jihua, Adhikari, Nirmal, Dubey, Ashish, Mitul, Abu Farzan, Mohammed, Lal, and Qiao, Qiquan. 2015. "Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells". United States. doi:10.1039/C5TA02709H. https://www.osti.gov/servlets/purl/1286906.
@article{osti_1286906,
title = {Improved performance by morphology control via fullerenes in PBDT-TBT-alkoBT based organic solar cells},
author = {Khatiwada, Devendra and Venkatesan, Swaminathan and Chen, QIliang and Chen, Jihua and Adhikari, Nirmal and Dubey, Ashish and Mitul, Abu Farzan and Mohammed, Lal and Qiao, Qiquan},
abstractNote = {In this work, we report improved performance by controlling morphology using different fullerene derivatives in poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b]dithiophene-alt-5,6-bis(dodecyloxy)-4,7- di(thieno[3,2-b]thiophen-2-yl)-benzo[c][1,2,5]thiadiazole} (PBDT-TBT-alkoBT) based organic solar cells. PC60BM and PC70BM fullerenes were used to investigate the characteristic change in morphology and device performance. Fullerene affects device efficiency by changing active layer morphology. PC70BM with broader absorption than PC60BM resulted in reduced device performance which was elucidated by the intermixed granular morphology separating each larger grain in the PC70BM/polymer composite layer which created higher density of traps. However after adding additive 1,8-diiodooctane (DIO), the fibrous morphology was observed due to reduced solubility of polymer and increased solubility of PC70BM in chloroform. The fibrous morphology improved charge transport leading to increase in overall device performance. Atomic force microscopies (AFM), photo induced charge extraction by linearly increasing voltage (photo-CELIV), and Kelvin prove force microscope (KPFM) were used to investigate nanoscale morphology of active layer with different fullerene derivatives. For PC60BM based active layer, AFM images revealed dense fibrous morphology and more distinct fibrous morphology was observed by adding DIO. The PC70BM based active layer only exhibited intermixed granular morphology instead of fibrous morphology observed in PC60BM based active layer. However, addition of DIO in PC70BM based active layer led to fibrous morphology. When additive DIO was not used, a wider distribution of surface potential was observed for PC70BM than PC60BM based active layer by KPFM measurements, indicating 2 polymer and fullerene domains are separated. When DIO was used, narrower distribution of surface potential for both PC70BM and PC60BM based active layers was observed. Photo-CELIV experiment showed larger extracted charge carrier density and mobility in PC70BM/DIO film.},
doi = {10.1039/C5TA02709H},
journal = {Journal of Materials Chemistry. A},
number = 29,
volume = 3,
place = {United States},
year = {2015},
month = {7}
}

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