Directed Chiral Self-Assembly of Purely Organic Phosphors for Room-Temperature Circularly Polarized Phosphorescence

Abstract

Circularly polarized phosphorescence (CPP) is increasingly recognized in materials science for its unique applications in optoelectronic devices, chiral recognition, and bioimaging. This study underscores a novel directed chiral self-assembly strategy of purely organic phosphors into supramolecular nanostructures to achieve bright room-temperature circularly polarized phosphorescence (RT-CPP). RT-CPP molecules are built on an aromatic carbonyl structure having also Br to mix (n,π*) and (π,π*) characters and to enable the heavy atom effect. Side chains are rationally designed to have strong hydrogen bonding, van der Waals interactions, and a chiral center for directed chiral self-assembly into supramolecular nanostructures. The tightly packed resulting supramolecular nanostructures also impower efficient suppression of molecular motions, thereby minimizing non-radiative decay and facilitating bright CPP emission at room temperature. The developed self-assembled supramolecular structures exhibit RT-CPP with the dissymmetry factor (glum) of ≈10−3, a high phosphorescence quantum yield of 4.1%, and a rapid triplet decay time of 180 microseconds. The presented molecular design principle enabling RT-CPP from purely organic phosphors may pave the way for novel photonic materials.