σ‐Conjugation and H‐Bond‐Directed Supramolecular Self‐Assembly: Key Features for Efficient Long‐Lived Room Temperature Phosphorescent Organic Molecular Crystals

Abstract

Long‐lived room temperature phosphorescence from organic molecular crystals attracts great attention. Persistent luminescence depends on the electronic properties of the molecular components, mainly π‐conjugated donor–acceptor (D‐A) chromophores, and their molecular packing. Here, a strategy is developed by designing two isomeric molecular phosphors incorporating and combining a bridge for σ‐conjugation between the D and A units and a structure‐directing unit for H‐bond‐directed supramolecular self‐assembly. Calculations highlight the critical role played by the two degrees of freedom of the σ‐conjugated bridge on the chromophore optical properties. The molecular crystals exhibit RTP quantum yields up to 20 % and lifetimes up to 520 ms. The crystal structures of the efficient phosphorescent materials establish the existence of an unprecedented well‐organization of the emitters into 2D rectangular columnar‐like supramolecular structure stabilized by intermolecular H‐bonding.

Photophysics and Spin‐Physics Studies on Persistent Upconversion Luminescence from Nonlinearly Polarizable Ferroelectric‐Like Lattice Prepared by Orderly Packing Donor–Acceptor Structures under Multiphoton Excitation

“…The synthesis of CD49 compound was based on a two‐step procedure adapted from the literature: [ 45 ] 1) synthesis of 9‐ H ‐propargyl‐carbazole precursor and 2) Sonogashira cross‐coupling between 9‐propagylcarbazole and 3‐bromo‐5‐iodopyridine.…”

Spin-orbital coupling and slow phonon effects enabled persistent photoluminescence in organic crystal under isomer doping

“…Synthesis. The CD49 compound was synthesized according to the following twostep procedure 50 : (1) preparation of 9-H-propargylcarbazole and (2) its subsequent Sonogashira cross-coupling with 3-bromo-5-iodopyridine.…”

Structurally Nontraditional Bipolar Hosts for RGB Phosphorescent OLEDs: Boosted by a “Butterfly‐Shaped” Medium‐Ring Acceptor

“…In contrast, the long‐wavelength emission bands exhibit a significantly red‐shifted and broadened character with the increased polarity of the solvents, which is ascribed to the CT emission from the MeCz donor to the BP acceptor. Therefore, in MeCz‐BP , there may exist two possible stable excited states due to the high rotatability of the acyclic BP acceptor [13] . When the acyclic BP acceptor is locked by an ethylidene bridge, the rotatability of the acceptor is weakened, which could enable the suppression of the CT emission in MeCz‐EtBP .…”