Recent advances in room temperature phosphorescence of chiral organic materials

Abstract

Room temperature phosphorescence (RTP) in purely organic materials is an uncommon phenomenon of emission, which can be characterized by a long persistent luminescence after removal of the excitation source. In the recent years, RTP organic materials have received a considerable attention due to their high application potential in various advancing technologies, ranging from optoelectronic to biomedical applications. In parallel, many progresses have been achieved on the rationalization of this process and led to the emergence of innovative strategies aiming to achieve highest performances both in terms of phosphorescence efficiency and lifetime. While the topic is still on an ascendant development, the generation of circularly polarized phosphorescent (CPP) emission from purely organic molecules is by far much less explored and remains an impressive challenge. Still, the perspective of CPP materials appears as an interesting opportunity to answer several comprehensives issues existing in the field. In this article, we define, in a straightforward way, basic principles and key notions for the generation of RTP and CP luminescence (CPL) guiding the design toward CPP materials. After this brief insight, recent advances in the field of chiral organic RTP materials are discussed with an emphasis on their CP-RTP properties. Based on this development, the conclusion drawn allows establishing the next challenges and future opportunities standing in the field.

Initialing Circularly Polarized Room-Temperature Phosphorescence from Purely Organic Luminophore Aggregate

“…5 These results demonstrate that inhibiting nonradiative pathways is conducive to producing CP-RTP and stabilizing the excited state to improve the dissymmetry factor in the axial chirality scaffold of bidibenzo[b,d]furan. More importantly, in response to the unusual glum, 24 the results of axial-chiral bidibenzo[b,d]furan with different alkyl-chain lengths and Sisomer demonstrate that gradual amplification of glum is induced by suppressing molecular motions. The use of polymers in developing intelligent CP-RTP materials can be simply realized through physical mixing or chemical bonding .…”

Molecular design, synthesis, properties, and applications of organic triplet emitters exhibiting blue, green, red and white room-temperature phosphorescence

“…There are review articles on organic materials exhibiting RTP either covering a wide range of structural peculiarities and utility areas, or discussing narrow topics such as the work of metal-free polymer-based materials, 7 chiral organic materials 8 and co-crystals exhibiting RTP, 9 as well as boron-containing RTP compounds. 10 Despite the fact that the emission colours of organic compounds exhibiting RTP can significantly impact their potential applications, there is a lack of literature analysing and classifying them based on the emission colours.…”

High-Quality Circularly Polarized Organic Afterglow from Nonconjugated Amorphous Chiral Copolymers

“…Circularly polarized luminescence (CPL) from organic optoelectronic functional materials has received numerous attention due to their potential applications in organic light-emitting diodes, 3D displays, anticounterfeiting, chiral recognition sensors, ellipsometry-based tomography, etc. − To evaluate the quality of CPL, the luminescence dissymmetry factor ( g lum ), which can be gauged by the equation g lum = 2 × ( I L – I R )/( I L + I R ), was proposed, where I L and I R represent the intensities of the left-handed and right-handed CPL, respectively. , Numerous efforts have been devoted to improving the value of g lum through either chiral chemical engineering or supramolecular self-assembly strategies. − Nevertheless, it is challenging to apply CPL to chiral systems that are strongly luminescent with both large | g lum | and high photoluminescence (PL) quantum yield (PLQY), and most studies of CPL are focusing on fluorescent luminophores, thermally activated delayed fluorescence molecules, and phosphorescent metal complexes. − …”