TY - JOUR
T1 - Bulk Heterojunction Solar Cells
T2 - Insight into Ternary Blends from a Characterization of the Intermolecular Packing and Electronic Properties in the Corresponding Binary Blends
AU - Ashokan, Ajith
AU - Wang, Tonghui
AU - Coropceanu, Veaceslav
AU - Brédas, Jean Luc
N1 - Funding Information: This work was supported by the Office of Naval Research in the framework of Awards No. N00014‐17‐1‐2208 and No. N00014‐20‐1‐2110, as well as by the Georgia Institute of Technology and the University of Arizona. Publisher Copyright: © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/7/1
Y1 - 2020/7/1
N2 - While adding a third component to a binary blend in the active layer of an organic solar cell is a promising approach to improve device performance, the control of active-layer morphology also becomes more complex. Here, a combination of molecular dynamics simulations and long-range corrected density functional theory calculations is used to examine the intermolecular packing and electronic properties in two polymer donor/small-molecule acceptor binary blends, D/A1 (donor/acceptor1) and D/A2 (donor/acceptor2), in order to gain insight into the D/A1/A2 ternary blend. The focus is on the blends of the 4-(3-(2-decyltetradecyl)-5′-(2,3-difluoro-4-(5-methylthiophen-2-yl)phenyl)-[2,2′-bithiophen]-5-yl)-7-(4-(2-decyltetradecyl)-5-methylthiophen-2-yl)-5,6-difluoro-2-propyl-2H-benzo[d][1,2,3]triazole (PTFB-O) polymer donor with the 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(5-hexylthienyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC-Th) and 2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis(5-hexylthiophen-2-yl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(4-octylthiophene-5,2-diyl))-bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))-dimalononitrile (IEIC-Th) acceptors. The intermolecular packings and extent of mixing between the polymer donor and the acceptor in both binary blends are found to be similar, which is consistent with the well-mixed nature of the ITIC-Th:IEIC-Th phase and the quasi-linear evolution of open-circuit voltage as a function of ITIC-Th concentration in the PTFB-O:ITIC-Th:IEIC-Th ternary blend. The intermolecular packing patterns and electron-transfer rates among the acceptors are explored to rationalize the higher electron mobility found in the PTFB-O:ITIC-Th blend. The energetic distribution of the charge-transfer electronic states and non-radiative recombination rates are also evaluated to understand the difference in voltage losses between the binary blends.
AB - While adding a third component to a binary blend in the active layer of an organic solar cell is a promising approach to improve device performance, the control of active-layer morphology also becomes more complex. Here, a combination of molecular dynamics simulations and long-range corrected density functional theory calculations is used to examine the intermolecular packing and electronic properties in two polymer donor/small-molecule acceptor binary blends, D/A1 (donor/acceptor1) and D/A2 (donor/acceptor2), in order to gain insight into the D/A1/A2 ternary blend. The focus is on the blends of the 4-(3-(2-decyltetradecyl)-5′-(2,3-difluoro-4-(5-methylthiophen-2-yl)phenyl)-[2,2′-bithiophen]-5-yl)-7-(4-(2-decyltetradecyl)-5-methylthiophen-2-yl)-5,6-difluoro-2-propyl-2H-benzo[d][1,2,3]triazole (PTFB-O) polymer donor with the 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(5-hexylthienyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC-Th) and 2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis(5-hexylthiophen-2-yl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(4-octylthiophene-5,2-diyl))-bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))-dimalononitrile (IEIC-Th) acceptors. The intermolecular packings and extent of mixing between the polymer donor and the acceptor in both binary blends are found to be similar, which is consistent with the well-mixed nature of the ITIC-Th:IEIC-Th phase and the quasi-linear evolution of open-circuit voltage as a function of ITIC-Th concentration in the PTFB-O:ITIC-Th:IEIC-Th ternary blend. The intermolecular packing patterns and electron-transfer rates among the acceptors are explored to rationalize the higher electron mobility found in the PTFB-O:ITIC-Th blend. The energetic distribution of the charge-transfer electronic states and non-radiative recombination rates are also evaluated to understand the difference in voltage losses between the binary blends.
KW - active-layer morphology
KW - binary blends
KW - density functional theory calculations
KW - molecular dynamics simulations
KW - organic solar cells
KW - ternary blends
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U2 - 10.1002/adts.202000049
DO - 10.1002/adts.202000049
M3 - Article
SN - 2513-0390
VL - 3
JO - Advanced Theory and Simulations
JF - Advanced Theory and Simulations
IS - 7
M1 - 2000049
ER -