Enhancing Circularly Polarized Luminescence Dissymmetry Factor of Chiral Cylindrical Molecules to −0.56 through Intramolecular Short-Range Charge Transfer

Abstract

High-performance circularly polarized luminescent (CPL) materials have received wide attention recently by virtue of broad application in circularly polarized light-emitting diodes, 3D display, and encryption. Reaching both high luminescence efficiency and strong luminescence dissymmetry factor (g_lum) is still a challenging goal that requires continuous efforts. Herein, we performed a systematic theoretical investigation on the chiroptical properties of helical cylindrical molecules (−)-[4]cyclo-2,6-anthracene [(−)-[4]CA_2,6] and (P)-[4]cyclo-2,8-chrysenylene [(P)-[4]CC_2,8], and found that the unique and symmetric cylindrical structure could make the transition dipole moment components offset along the cylindrical surface but concentrated along the vertical central axis. This structural superiority contributes the collinear electric and magnetic transition dipole moment vectors and thus the large g_lum. Based on the results of decomposed transition dipole moment vectors to individual atoms, an effective strategy to enhance the g_lum through introducing intramolecular short-range charge transfer by embedding B,N atoms is proposed. The decreased electric transition dipole moment and well-kept magnetic transition dipole moment enable the g_lum of B,N-embedded designed molecules (−)-[4]CA_2,6-4BN and (P)-[4]CC_2,8-4BN up to −0.31 and −0.56, respectively. This molecular-insight investigation deepens the understanding of the structure–property relationship and provides efficient guidance for improving g_lum of CPL materials.