Chiral
supramolecular assembly can provide a powerful strategy
for developing circularly polarized luminescence (CPL)-active materials
by forming helices or superhelices into single or multiple components.
Herein, we chose three achiral liquid crystal polymers (LC-P1/P2/P3) and chiral binaphthyl-based inducers (
R/S
-M) with anchored dihedral angles
to construct chiral co-assemblies and explore the induced CPL behavior
from pyrenyl (Py) emitters in achiral LC polymers through the regulation
of helical nanofibers during the supramolecular co-assembly process.
Most interestingly, chiral co-assembly (
R/S-
M)
0.1
-(P3)
0.9
emitted an inverted blue-colored
CPL signal during thermal annealing treatment at the glass transition
temperature due to the flexible main chain of the LC polymer (LC-P3). The strongest blue-colored CPL emission for the (
R/S-
M)
0.1
-(P3)
0.9
spin-coated
film (λem = 455 nm, |g
em| = 6.47 × 10–2, ΦF = 48.5%)
could be detected by using thermal annealing treatment at 105 °C.
Two chiral binaphthyl polymers (R/S-P1 and R/S-P2) with different dihedral angles of the binaphthyl moiety were chosen as chiral inducers to construct chiral co-assemblies with an achiral pyrene-naphthalimide dye (NPy) and then acted as the emitting layer (EML) of circularly polarized electroluminescence (CP-EL) devices. The anchored dihedral angle of R/S-P2 not only exhibited the enhanced chirality signal, but also had a strong chirality-inducing effect on the achiral NPy dye in the chiral co-assembly (R/S-P2) 0.6 -(NPy) 0.4 . After annealing at 120 °C, the CPL signal (j g em j) of ordered helical nano-fibers (R/S-P2) 0.6 -(NPy) 0.4 was amplified to 5.6 × 10 À 2 , which was about 6-fold larger than that of (R/ S-P1) 0.6 -(NPy) 0.4 . The amplified g em value of (R/S-P2) 0.6 -(NPy) 0.4 was due to the formation of a helical co-assembly through the strong π-π stacking interaction between the R/S-P2 and the achiral NPy. This kind of ordered helical nanofibers (R/S-P2) 0.6 -(NPy) 0.4 acted as the EML of CP-OLEDs, and achieved an excellent CP-EL performance (j g EL j = 4.8 × 10 À 2 ).
Recently, much attention has been paid to circularly polarized luminescence (CPL) organic light-emitting diodes (CP-OLEDs) from achiral fluorophore through intermolecular chirality induction mechanism. In this paper, we developed a new...
Chiral supramolecular assembly has been assigned to be one of the most favorable strategies for the development of excellent circularly polarized luminescent (CPL)-active materials. Herein, we report our study of an achiral boron-containing pyrene (Py)-based chromophore (PyBO) as a circularly polarized excimer emission (CPEE) dye induced by chiral co-assemblies containing chiral binaphthyl-based enantiomers (R/S-M). Chiral co-assembly R/S-M-(PyBO)4 fresh film spin-coated from toluene solution can exhibit orderly nanofibers and strong green CPEE (λem = 512 nm, gem = ±0.45, ΦFL = 51.2 %) resulting from an achiral PyBO excimer. In contrast, only a very weak blue CPL was observed (λem = 461 nm, gem = ± 0.0125, ΦFL = 19.0 %) after 187 h due to PyBO monomer emission as spherulite growth. Interestingly, this kind of chiral co-assembly R-M-(PyBO)4-T film from tetrahydrofuran (THF) solution retains uniform morphology and affords the most stable and strongest CPEE performance (λem = 512 nm, gem = + 0.62, ΦFL = 53.3 %) after 10 days.
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