Enhancing Photovoltaic Performance of Nonfused-Ring Electron Acceptors
via Asymmetric End-group Engineering and Noncova-lently Conformational
Locks
Abstract
By employing the asymmetric end-group engineering, an asymmetric
nonfused-ring electron acceptors (NFREAs) was designed and synthesized.
Compared with the symmetric analogs (NoCA-17 and NoCA-18), NoCA-19
possesses broader light absorption range, more coplanar π-conjugated
backbone, and appropriate crystallinity according to the experimental
and theoretical results. The organic solar cells based on J52:NoCA-19
exhibited a power conversion efficiency as high as 12.26%, which is
much higher than those of J52:NoCA-17 (9.50%) and J52:NoCA-18
(11.77%), mainly due to more efficient exciton dissociation, better and
balanced charge mobility, suppressed recombination loss, shorter charge
extraction time, longer charge carrier lifetimes, and more favorable
blend film morphology. These findings demonstrate the great potential of
asymmetric end-group engineering in exploring low-cost and
high-performance NFREAs.