TY - JOUR
T1 - Stable Postfullerene Solar Cells via Direct C-H Arylation Polymerization. Morphology-Performance Relationships
AU - Aldrich, Thomas J.
AU - Zhu, Weigang
AU - Mukherjee, Subhrangsu
AU - Richter, Lee J.
AU - Gann, Eliot
AU - DeLongchamp, Dean M.
AU - Facchetti, Antonio
AU - Melkonyan, Ferdinand S.
AU - Marks, Tobin J
PY - 2019/1/1
Y1 - 2019/1/1
N2 - The scope of the environmentally benign direct C-H arylation polymerization (DARP) process is validated and significantly extended in the synthesis of a high-performance benzodithiophene-based copolymer series, PBDT(Ar)-FTTE, with previously untested and systematically varied heteroaryl (Ar) substituents. Bulk-heterojunction (BHJ) polymer solar cells (PSCs) containing the high-performance nonfullerene acceptor (NFA) ITIC-Th and DARP-derived donors are fabricated and evaluated, yielding PCEs as high as 8%. The relationships between Ar-sensitive copolymer structure, BHJ morphology, and PSC performance are elucidated through in-depth characterization of structural order, phase separation, and charge transport using SCLC, AFM, GIWAXS, R-SoXS, and NEXAFS measurements, which conclusively demonstrate the important effects of Ar-tunable, dimensionally smaller, and well-blended copolymer domains for maximum PSC performance. Smaller BHJ copolymer domains having greater ITIC-Th miscibility definitively correlate with enhanced JSC, FF, and PCE metrics. Surprisingly regarding cell performance durability, while unencapsulated PBDTT-FTTE:ITIC-Th PSCs deliver the highest initial PCE, the unencapsulated PBDTTF-FTTE:ITIC-Th devices exhibit the optimum combination of high initial photovoltaic metrics and stability, retaining nearly 90% of the initial PCE after 51 days in ambient conditions and 83% of initial PCE after 180 min under simulated solar illumination. Importantly, for this PBDT(Ar)-FTTE:ITIC-Th series, PSC photovoltaic stability correlates with the presence of large pure BHJ domains, and moreover rivals or exceeds the stability of the analogous fullerene-based PSCs. Together, these results argue that solar cells prepared with the environmentally benign DARP process and NFAs are promising for both greener and more stable solar energy generation.
AB - The scope of the environmentally benign direct C-H arylation polymerization (DARP) process is validated and significantly extended in the synthesis of a high-performance benzodithiophene-based copolymer series, PBDT(Ar)-FTTE, with previously untested and systematically varied heteroaryl (Ar) substituents. Bulk-heterojunction (BHJ) polymer solar cells (PSCs) containing the high-performance nonfullerene acceptor (NFA) ITIC-Th and DARP-derived donors are fabricated and evaluated, yielding PCEs as high as 8%. The relationships between Ar-sensitive copolymer structure, BHJ morphology, and PSC performance are elucidated through in-depth characterization of structural order, phase separation, and charge transport using SCLC, AFM, GIWAXS, R-SoXS, and NEXAFS measurements, which conclusively demonstrate the important effects of Ar-tunable, dimensionally smaller, and well-blended copolymer domains for maximum PSC performance. Smaller BHJ copolymer domains having greater ITIC-Th miscibility definitively correlate with enhanced JSC, FF, and PCE metrics. Surprisingly regarding cell performance durability, while unencapsulated PBDTT-FTTE:ITIC-Th PSCs deliver the highest initial PCE, the unencapsulated PBDTTF-FTTE:ITIC-Th devices exhibit the optimum combination of high initial photovoltaic metrics and stability, retaining nearly 90% of the initial PCE after 51 days in ambient conditions and 83% of initial PCE after 180 min under simulated solar illumination. Importantly, for this PBDT(Ar)-FTTE:ITIC-Th series, PSC photovoltaic stability correlates with the presence of large pure BHJ domains, and moreover rivals or exceeds the stability of the analogous fullerene-based PSCs. Together, these results argue that solar cells prepared with the environmentally benign DARP process and NFAs are promising for both greener and more stable solar energy generation.
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U2 - 10.1021/acs.chemmater.9b01741
DO - 10.1021/acs.chemmater.9b01741
M3 - Article
AN - SCOPUS:85067054596
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
ER -