Extended Conjugation Length of Nonfullerene Acceptors
with Improved Planarity via Noncovalent Interactions for High-Performance
Organic Solar Cells
Liu, DX (Liu, Dongxue)[ 1,2 ] ; Kan, B (Kan, Bin)[ 1,2 ] ; Ke, X (Ke, Xin)[ 1,2 ] ; Zheng, N (Zheng, Nan)[ 3 ] ; Xie, ZQ (Xie, Zengqi)[ 3 ] ; Lu, D (Lu, Di)[ 1,2 ] ; Liu, YS(Liu, Yongsheng)[ 1,2 ]
ADVANCED
ENERGY MATERIALS, 2018, 8(26): 文献号: 1801618
DOI: 10.1002/aenm.201801618
WOS:000444537800023
Abstract
Three
low-bandgap nonfullerene acceptors (NFAs) IDTO-T-4F, IDTO-Se-4F, and IDTO-TT-4F
with extended conjugation length are designed and synthesized. Various
pi-spacers, thiophene, selenophene, and thieno[3,2-b]thiophene are incorporated
to extend the conjugated length and enhance the backbone planarity via
noncovalent O center dot center dot center dotS or O center dot center dot
center dot Se interactions. These NFAs exhibit strong light absorption in the
range of 600-900 nm with narrow bandgaps between 1.38 and 1.45 eV. By blending
with a wide-bandgap donor material PBDB-T, organic solar cells (OSCs) based on
these NFAs all yield high efficiency over 10% with low energy losses ranging
from 0.52 to 0.59 eV. Importantly, as a result of relatively high lowest
unoccupied molecular orbital level, large hole and electron mobility in blend
film, and low charge carrier recombination loss, optimized devices based on
IDTO-T-4F exhibit a large open-circuit voltage of 0.864 V, a high short-circuit
current density of 20.12 mA cm(-2), and a notable fill factor of 72.7%, leading
to an impressive efficiency of 12.62%, which represents the best performance
for NFA OSCs using noncovalent interactions in acceptor molecule design. The
results indicate that optimizing the conjugation length and backbone planarity
via intramolecular noncovalent O center dot center dot center dotS or O center
dot center dot center dot Se interactions is a useful strategy for NFA
materials invention toward high-performance solar cells.
