Understanding Aggregation Induced Emission in a Propeller‐Shaped Blue Emitter

Abstract

Organic fluorophores with an enhanced emission in the condensed phase have great potential for the design of optoelectronic materials. Several propeller-shaped molecules show aggregation-induced emission (AIE), in particular, silole derivatives have attracted wide attention because of their significant quantum yields in the solid state. In this contribution, we investigate the mechanism of AIE of a propeller-shaped blue emitter: 1,2,3,4-tetraphenyl-1,3-cyclopentadiene (TPC). We explore the excited state mechanism in the light of models most commonly used to explain it: restriction of intramolecular motions (RIM) and restricted access to the conical intersection (RACI). Our interpretation is supported by excited state dynamics simulations and the analysis of Huang-Rhys factors and reorganisation energies. We quantify the effects of intermolecular interactions and exciton couplings. The mechanism for TPC is compared with previous investigations of analogue silole compounds. Our systematic investigation highlights the role of conical intersections on the nonradiative decay mechanisms and complementary descriptions provided by the RIM and RACI models.[a] Dr.

fromage: A library for the study of molecular crystal excited states at the aggregate scale

“…. The diabatization method has already been employed in fromage to investigate the aggregate behavior of propeller‐shaped emitters …”

Donor and acceptor engineering for BINOL based AIEgens with enhanced fluorescence performance

“…In the solid state, the quenched emission of 1d and 2d should be ascribed to the exciton coupling between each molecule due to the large electron density overlap by the enhanced electron donating-accepting effect. 33 To better understand the steric hindrance of the substituents, we have studied two monosubstituted products 1a and 2a. The QY of 1a and 2a in the solid state is 3.1% and 4.43%, respectively.…”

Unsymmetrical 2,4,6‐Triarylpyridines as Versatile Scaffolds for Deep‐Blue and Dual‐Emission Fluorophores

“…[11][12][13] One limitation of organic chromophores lies on the difficulty to obtain deep blue emission with high efficiency, [14] due to the intrinsic wide band gap required for the blue color. [15] Heteroaromatic chromophores bearing twisted aromatic substituents have emerged as promising candidates for deep blue emission, [15,16] sometimes through thermally activated delayed fluorescence. [17] This goal is difficult to reach, because fluorophores bearing aromatic substituents which can rotate freely often present very small quantum yields in solution, due to non-radiative relaxation, and only emit when those rotations are restricted, for example in aggregate [4,13,18,19] or crystalline state, [5] or when they interact with macromolecules.…”