An A-D-A Type Small-Molecule Electron Acceptor with
End-Extended Conjugation for High Performance Organic Solar Cells
Feng, HR (Feng, Huanran)[ 1,2 ] ; Qiu, NL (Qiu, Nailiang)[ 1,2 ] ; Wang, X (Wang, Xian)[ 3 ] ; Wang, YC (Wang, Yunchuang)[ 1,2 ] ; Kan, B (Kan, Bin)[ 1,2 ]; Wan, XJ (Wan, Xiangjian)[ 1,2 ] ; Zhang, MT (Zhang, Mingtao)[ 1,2 ] ; Xia, AD (Xia, Andong)[ 3 ] ; Li, CX (Li, Chenxi)[ 1,2 ] ; Liu, F (Liu, Feng)[ 4 ] ; Zhang, HT(Zhang,
Hongtao)[ 1,2 ] ; Chen, YS (Chen,
Yongsheng)[ 1,2 ]
CHEMISTRY OF
MATERIALS, 2017, 29(18): 7908-7917
DOI: 10.1021/acs.chemmater.7b02811
WOS:000411918900033
Abstract
A new
non-fullerene small molecule with an acceptor-donor-acceptor (A-D-A) structure,
FDNCTF, incorporating fluorenedicyclopentathiophene as core and naphthyl-fused
indanone as end groups, was designed and synthesized. Compared with the
previous molecule FDICTF with the phenyl-fused indanone as the end groups, the
extended pi-conjugation at the end group has only little impact on its
molecular orbital energy levels, and thus, the open-circuit voltage (V-oc) of
its solar cell devices has been kept high. However, its light absorption and
mobility, together with the short-current density (J(sc)) and the fill factor
(FF), of its devices have been all improved simultaneously. Through morphology,
transient absorption, and theoretical studies, it is believed that these
favorable changes are caused by (1) the appropriately enhanced molecular
interaction between donor/acceptor which makes the charge separation at the
interface more efficient, and (2) enhanced light absorption and more ordered
packing at solid state, all due to the extended end-group conjugation of this
molecule. With these, the solar cells with FDNCTF as the acceptor and a wide
band gap polymer PBDB-T as the donor demonstrated a high power conversion
efficiency (PCE) of 11.2% with an enhanced J(sc) and a maintained high V-oc,
and significantly improved FF of 72.7% compared with that of the devices of
FDICTF with the phenyl-fused indanone as the end groups. These results indicate
that the unexplored conjugation size of the end group plays a critic role for
the performance of their solar cell devices.
