The incorporation of multiple donors into the bulk-heterojunction layer of organic polymer solar cells (PSCs) has been demonstrated as a practical and elegant strategy to improve photovoltaics performance. However, it is challenging to successfully design and blend multiple donors, while minimizing unfavorable interactions (e.g., morphological traps, recombination centers, etc.). Here, a new Förster resonance energy transfer-based design is shown utilizing the synergistic nature of three light active donors (two small molecules and a high-performance donor–acceptor polymer) with a fullerene acceptor to create highly efficient quaternary PSCs with power conversion efficiencies (PCEs) of up to 10.7%. Within this quaternary architecture, it is revealed that the addition of small molecules in low concentrations broadens the absorption bandwidth, induces cocrystalline molecular conformations, and promotes rapid (picosecond) energy transfer processes. These results provide guidance for the design of multiple-donor systems using simple processing techniques to realize single-junction PSC designs with unprecedented PCEs. A viable strategy to realize highly efficient quaternary blend solar cells is introduced that breaks efficiency above 10% with complementary squaraine small molecules–low band-gap polymer combinations. Our quaternary design demonstrates several advantages: (i) broader light absorption, (ii) improved surface morphology, (iii) enhanced cocrystallization packing, (iv) multiple energy and charge transfer pathways to reduce recombination, and (v) increased charge mobility.

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frster resonance energy transferbased design quaternary design energy and charge transfer small singlejunction psc designs processing cocrystalline molecular conformations bulkheterojunction layer highperformance donoracceptor light active donors surface morphology morphological traps recombination centers enhanced cocrystallization packing quaternary blend solar cells picosecond energy transfer multipledonor systems bandgap polymer charge mobility fullerene acceptor absorption

André D. Taylor, Patrick R. Melvin, Minjoo L. Lee, Kevin G. Yager, Xiao Tong, Nilay Hazari,Tenghooi Goh, Matthew Y. Sfeir, Francisco Antonio, Chang-Yong Nam, Louise M. Guard, Jing-Shun Huang, Benjamin G. Bartolome,.Quaternary Organic Solar Cells Enhanced by Cocrystalline Squaraines with Power Conversion Efficiencies >10%. 6 (21),.

André D. Taylor, et al."Quaternary Organic Solar Cells Enhanced by Cocrystalline Squaraines with Power Conversion Efficiencies >10%" 6

André D. Taylor, Patrick R. Melvin, Minjoo L. Lee, Kevin G. Yager, Xiao Tong, Nilay Hazari,Tenghooi Goh, Matthew Y. Sfeir, Francisco Antonio, Chang-Yong Nam, Louise M. Guard, Jing-Shun Huang, Benjamin G. Bartolome,"Quaternary Organic Solar Cells Enhanced by Cocrystalline Squaraines with Power Conversion Efficiencies >10%"