Journal
ADVANCED ENERGY MATERIALS
Volume 12, Issue 18, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202103957
Keywords
charge generation; charge transport; film morphology; molecular packing; nonfullerene acceptors
Categories
Funding
- Office of Naval Research [N00014-19-1-2453]
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-76SF00515]
- National Science Foundation [ECCS-1542152]
- US Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-FG02-99ER14999]
- NIST-NRC postdoctoral fellowship program
- DOE Office of Science [DESC0012704]
Ask authors/readers for more resources
Molecular aggregation and crystallization during film coating are crucial for high-performing organic photovoltaics. The authors demonstrate that using twisted acceptor-donor-acceptor compounds leads to the formation of mostly amorphous phases in the as-cast film, which can be converted into more crystalline domains through thermal annealing. This design strategy improves the charge transport efficiency by achieving an optimal morphology.
Molecular aggregation and crystallization during film coating play a crucial role in the realization of high-performing organic photovoltaics. Strong intermolecular interactions and high solid-state crystallinity are beneficial for charge transport. However, fast crystallization during thin-film drying often limits the formation of the finely phase-separated morphology required for efficient charge generation. Herein, the authors show that twisted acceptor-donor-acceptor (A-D-A) type compounds, containing an indacenodithiophene (IDT) electron-rich core and two naphthalenediimide (NDI) electron-poor units, leads to formation of mostly amorphous phases in the as-cast film, which can be readily converted into more crystalline domains by means of thermal annealing. This design strategy solves the aforementioned conundrum, leading to an optimal morphology in terms of reduced donor/acceptor domain-separation sizes (ca. 13 nm) and increased packing order. Solar cells based on these acceptors with a PBDB-T polymer donor show a power conversion efficiency over 10% and stable morphology, which results from the combined properties of desirable excited-state dynamics, high charge mobility, and optimal aggregation/crystallization characteristics. These results demonstrate that the twisted A-D-A motif featuring thermally-induced crystallization behavior is indeed a promising alternative design approach toward more morphologically robust materials for efficient organic photovoltaics.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available