TY - JOUR
T1 - Controlling Energy Levels and Blend Morphology for All-Polymer Solar Cells via Fluorination of a Naphthalene Diimide-Based Copolymer Acceptor
AU - Uddin, Mohammad Afsar
AU - Kim, Youngkwon
AU - Younts, Robert
AU - Lee, Wonho
AU - Gautam, Bhoj
AU - Choi, Joonhyeong
AU - Wang, Cheng
AU - Gundogdu, Kenan
AU - Kim, Bumjoon J.
AU - Woo, Han Young
N1 - Funding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2015R1A2A1A15055605, 2012M3A6A7055540). This work was also supported by the New and Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), Korea (No. 20133030011330). This work was also supported by Office of Naval Research (ONR) grant N000141310526 (B.R.G., R.Y., and K.G).
Publisher Copyright:
© 2016 American Chemical Society.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2016/9/13
Y1 - 2016/9/13
N2 - We investigate the photovoltaic properties and charge dynamics of all polymer solar cells (all-PSCs) based on poly[(N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)) and its fluorinated analogue, poly[(N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(3,3′-difluoro-2,2′-bithiophene)] (P(NDI2OD-T2F)), as the acceptor polymer and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-alt-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione] (PBDTTTPD) as the donor polymer. The PBDTTTPD:P(NDI2OD-T2)-based device has a high open-circuit voltage (VOC) of 1.03 V but suffers from low power conversion efficiency (PCE) of 2.02% with a short-circuit current density (JSC) and fill factor (FF) of 4.45 mA cm-2 and 0.44, respectively. In a stark contrast, the PCE of PBDTTTPD:P(NDI2OD-T2F)-based PSC dramatically increases to 6.09% (VOC = 1.00 V, JSC = 11.68 mA cm-2, and FF = 0.52). These results are attributed to the fluorination, which removes the energetic barrier for hole transfer and promotes the formation of the donor/acceptor blend morphology with suppressed phase separation and enhanced intermixed phases. The detailed charge dynamics examined by femtosecond transient absorption spectroscopy suggests the significantly increased hole transfer efficiency and larger populations of long-lived polarons for PBDTTTPD:P(NDI2OD-T2F).
AB - We investigate the photovoltaic properties and charge dynamics of all polymer solar cells (all-PSCs) based on poly[(N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)) and its fluorinated analogue, poly[(N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(3,3′-difluoro-2,2′-bithiophene)] (P(NDI2OD-T2F)), as the acceptor polymer and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-alt-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione] (PBDTTTPD) as the donor polymer. The PBDTTTPD:P(NDI2OD-T2)-based device has a high open-circuit voltage (VOC) of 1.03 V but suffers from low power conversion efficiency (PCE) of 2.02% with a short-circuit current density (JSC) and fill factor (FF) of 4.45 mA cm-2 and 0.44, respectively. In a stark contrast, the PCE of PBDTTTPD:P(NDI2OD-T2F)-based PSC dramatically increases to 6.09% (VOC = 1.00 V, JSC = 11.68 mA cm-2, and FF = 0.52). These results are attributed to the fluorination, which removes the energetic barrier for hole transfer and promotes the formation of the donor/acceptor blend morphology with suppressed phase separation and enhanced intermixed phases. The detailed charge dynamics examined by femtosecond transient absorption spectroscopy suggests the significantly increased hole transfer efficiency and larger populations of long-lived polarons for PBDTTTPD:P(NDI2OD-T2F).
UR - http://www.scopus.com/inward/record.url?scp=84987670190&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84987670190&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.6b01414
DO - 10.1021/acs.macromol.6b01414
M3 - Article
AN - SCOPUS:84987670190
SN - 0024-9297
VL - 49
SP - 6374
EP - 6383
JO - Macromolecules
JF - Macromolecules
IS - 17
ER -
