Customizing Circularly Polarized Afterglow by Stepwise Chiral Amplification in BINAPs/BINAPOs

Abstract

Overcoming spin-forbidden radiation in chiral phosphors has attracted enormous attention because of their capacity in circularly polarized organic ultra-long room temperature phosphorescence (CP-OURTP). However, their developments have been hindered by the short lifetimes and low dissymmetry factors, which is attributed to the differing parity selection rules that govern the electric and magnetic dipole moments in chiral molecules, as well as poor triplet populations via intersystem crossing (ISC). Taking stepwise chiral amplification at molecular and supramolecular aspects, herein, we firstly reported the donor-decorative BINAPs/BINAPOs with tunable D–A character and triplet incubation, which could enable hybridized local and charge-transfer (HLCT) characteristics, heavy atoms, and p−π* effects. These emitters could serve as guests in the polymer matrix. The doped phosphorescent polymer exhibits unimolecular circularly polarized luminescence with high quantum efficiency, impressive CP-OURTP lifetimes (up to 1.02 s), and decent dissymmetry factors (10−3 level). Comprehensive studies unveil that the impressive CP-OURTP from monomer emission is ascribed to the 1HLCT-controlled ISC and long-lived 3LE-governing triplet radiation, as well as superior electric-magnetic dipole moment environments. Moreover, given the high RTP activity of rigid polymerization, we demonstrate the potential application in CP-OURTP amplification. Using in-situ chiral liquid crystal polymerization, RM257 liquid crystal doped with 0.1−1.0 wt% PO1 guests demonstrate a secondary helical assembly, showing an amplified gCP-RTP factor (±0.11) and a long lifetime (0.83 s) after photopolymerization. The current materials' excellent performance in CP-OURTP and structural dependence could function as afterglow patterns for multiple optical encryption.