Nonfullerene/Fullerene
Acceptor Blend with a Tunable
Energy State for High-Performance Ternary Organic Solar Cells
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Abstract
Ternary
blending is an effective strategy for broadening the absorption
range of the active layer in bulk heterojunction polymer solar cells
and for constructing an efficient cascade energy landscape at the
donor/acceptor interface to achieve high efficiencies. In this study,
we report efficient ternary blend solar cells containing an acceptor
alloy consisting of the indacenodithiophene-based nonfullerene material,
IDT2BR, and the fullerene material, phenyl-C<sub>71</sub>-butyric
acid methyl ester (PC<sub>71</sub>BM). The IDT2BR materials mix fully
with PC<sub>71</sub>BM materials, and the energy state of this phase
can be tuned by varying the blending ratio. We performed photoluminescence
and external quantum efficiency studies and found that the ternary
charge cascade structure efficiently transfers the photogenerated
charges from the polymer to IDT2BR and finally to PC<sub>71</sub>BM
materials. Ternary blend devices containing the IDT2BR:PC<sub>71</sub>BM acceptor blend and various types of donor polymers were found
to exhibit power conversion efficiencies (PCEs) improved by more than
10% over the PCEs of the binary blend devices