Aggregate‐induced emission in light‐emitting liquid crystal display technology

Abstract

Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture.

Synthesis, Aggregation-Induced Emission, and Liquid Crystalline Structure of Tetraphenylethylene–Surfactant Complex via Ionic Self-Assembly

“…Because of their unique combination of optophysical and anisotropic organization features within a liquid crystalline phase, luminescent liquid crystals (LCs) have attracted great attention for optoelectronic applications such as organic light-emitting diodes, − imaging systems, , light-emitting LC displays, , and organic semiconductors . However, most conventional luminogens are highly emissive in solution but will be weak or be quenched in the aggregated state due to the aggregation-caused quenching (ACQ) effect, − which ultimately limits the use of luminophores in optoelectronic devices.…”

“…Since then, researchers have reported abundant AIE − or aggregation-induced emission enhancement (AIEE) − materials, which are not luminescence or weak in solution but exhibit strong fluorescence in aggregation or solid state. Among all the AIE luminogens, tetraphenylethylene (TPE) is usually employed due to its high solid-state emission efficiency and versatile functionalization approach. , The AIE effect provides the possibility to fabricate novel AIE-active LCs by introducing peripheral mesogens or long flexible groups to the AIE cores. − Recently, the research on AIE-active LCs is truly an area with tantalizing prospect due to the real-world applications, especially in the fabrication of light-emitting LC devices. , For example, a group of such LC systems have been built with TPE core decorated with either flexible alkyl/alkoxy tails or mesogenic units . However, most synthesis methods for these AIE LCs require complex and harsh conditions, and often the yield is relatively low.…”

A Fluorescence Sensor for Pb2+ Detection Based on Liquid Crystals and Aggregation-Induced Emission Luminogens

“…Aggregation-induced emission is an extraordinary photophysical phenomenon that is the opposite of aggregation-induced quenching, where the AIE fluorogens are highly emissive in aggregation due to the restriction of rotation within the molecule. − These materials have attracted significant attention in various fields such as luminescent materials, sensors, bioimaging, biology delivery, and theranostics. , Several research works have reported the combination of AIE materials with liquid crystals, such as the work by Zhao et al who demonstrated light-emitting liquid crystal displays and reported their performance under an electric field based on an AIE luminogen obtained by synthesizing an AIE-LC material. − It is expected that AIE luminogens will enable fluorescence LC-based sensors and largely decrease the limit of detection in the probes, compared to previous naked eye-based LC sensors.…”

A stabilized lamellar liquid crystalline phase with aggregation-induced emission features based on pyrrolopyrrole derivatives

“…The development and utilization of liquid crystals (LCs) has made significant advances. 1,2 In recent years, luminescent display materials, such as light-emitting liquid crystalline (LC) displays, [3][4][5][6][7][8][9] organic light-emitting diodes, 10,11 organic optoelectronics, 12,13 and sensors, [14][15][16][17] have attracted researchers' interests due to their growing applications and requirements. However, many luminescent molecules are highly emissive in solution but quenched in aggregate states.…”

“…The published AIE-LC research works mainly focused on employing TPE as AIE-active cores. 5,6,9,11,[27][28][29][30][31] Fewer other kinds of AIE units have been adopted to synthesize AIE-LC compounds. 14,[32][33][34][35] In this paper, we constructed AIE-LCs based on the AIEgens of 1,2,4,5-tetraphenyl-1,4-dihydropyrrolo[3,2-b]-pyrrole (TPPP) developed by our groups.…”