Perylene Bisimide-Based Luminescent Liquid Crystals with Tunable Solid-State Light Emission

Abstract

Perylene bisimides are among the most studied building blocks for supramolecular assemblies in the fabrication of optoelectronic devices for their exceptional optical and electronic properties; however, developing perylene bisimide-based luminescent liquid crystals remains a challenge for the strong π-stacking tendency of the large planar aromatic core to quench the emission. We here reported a novel strategy to achieve luminescent liquid crystals based on perylene bisimides by introducing a conformation-adjustable core to control the molecular stacking arrangement of planar perylene bisimides in the solid state. The emission wavelength is in the deep-red region with a luminescence efficiency of up to 10%. Fluorescence properties of the liquid crystals can be further regulated by photoisomerization-induced structural evolution from columnar to lamellar mesophases. These luminescent liquid crystals are also able to not only exhibit strong emission at high temperatures but also show attractive thermochromic luminescence tuning behaviors. This work provides a new strategy for the design and development of novel solid-state luminescent materials with potential for various optoelectronic applications.

Supramolecular coassembly: monomer pair design, morphology regulation and functional application

“…4c). 48 The fluorescence properties of the obtained liquid crystal can be regulated by photoisomerization-induced structural evolution from columnar to lamellar mesophases. As for the electro-fluorochromic example, we have reported a novel 1,8-dioxapyrene-based SCA, through the coordination of terpyridine ligands on M 1 and M 2 with Eu 3+ ions (Fig.…”

“…4c). 48 The supramolecular complexes could form a 1D columnar mesophase in hexagonal symmetry. Furthermore, adjusting the spatial geometry of the TCS core by the photoinduced Z – E isomerization allowed LC structure evolution from columnar to lamellar mesophases.…”

“…4c). 48 Moreover, these luminescent liquid crystals were also able to not only exhibit strong emission at high temperatures but also show attractive thermochromic luminescence tuning behaviors. Besides the tuning and application of common light emissions, our group and Liu's group further applied the SCAs in the area of CPL.…”

“…40,41 Thus, the functions have to depend on the nature of the carriers and hence can be easily tuned via post-modification. Alternatively, if some functional elements, including catalyst, 42,43 chromophores, [44][45][46][47][48][49][50][51] electro-active moieties, [52][53][54][55][56] and bioactive moieties [57][58][59][60][61][62] have been incorporated into the monomers, the functions of SCAs are usually determined at an early stage of monomer pair design. Due to the more direct correlation of functions and molecular structures, this class of SCAs has been widely applied in catalytic, optical and electrical, and biomedical fields.…”

Fluorescent Polymers Conspectus

“…Luminous liquid crystals (LLCs) combining intrinsic light-emitting properties and liquid crystalline ordering have piqued interest in recent decades due to their potential applications as emissive liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), sensors, and optical information storage. [ 135 , 136 , 137 , 138 , 139 ] Xie et al [ 140 ], using AIE luminogens, were able to successfully manufacture a series of novel, highly efficient luminous liquid crystalline polymer (LCPs), namely poly{2,5-bis{[2-(4-oxytetraphenylethylene)-n-alkyl]oxycarbonyl}styrene}, with different chain lengths (m = 2, 4, 6, 8, 10, 12), as show in Figure 18 . LCPs are polymers with liquid crystal properties and frequently contain aromatic rings as mesogens.…”