Boosting Circularly Polarized Luminescence of Organic Conjugated Systems <i>via</i> Twisted Intramolecular Charge Transfer
Junfeng Li, Chenxi Hou, Chao Huang, Shanqi Xu, Xuelei Peng, Qi Qi, Wen‐Yong Lai, Wei Huang
Abstract
Realizing a high luminescence dissymmetry factor ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>lum</mml:mtext> </mml:mrow> </mml:msub> </mml:math> ) is a paramount yet challenging issue in the research field of circularly polarized luminescence (CPL). Here, we reported a novel set of organic conjugated systems with twisted intramolecular charge transfer (TICT) characteristics based on conjugated o -carborane-binaphthyl dyads composing of binaphthyl units as chiral electron donors and o -carborane units as achiral electron acceptors, demonstrating intense CPL with large <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>lum</mml:mtext> </mml:mrow> </mml:msub> </mml:math> values. Interestingly, single-crystalline o -1 exhibited a high-level brightness and a large <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>lum</mml:mtext> </mml:mrow> </mml:msub> </mml:math> factor as high as +0.13, whereas single-crystalline o -2 processed a relatively low brightness with a decreased <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> <mml:mrow> <mml:mtext>lum</mml:mtext> </mml:mrow> </mml:msub> </mml:math> value to -0.04. The significant diversity of CPL-active properties was triggered by the selective introduction of o -carborane units onto the binaphthyl units. Benefiting from the large magnetic dipole transition moments in TICT states, the CPL activity of TICT o -carborane-based materials exhibited amplified circular polarization. This study provides an efficient molecular engineering strategy for the rational design and development of highly efficient CPL-active materials.