Development, mechanistic study and electro-, chemi- and mechanoluminescence of aggregation-induced emission materials

Abstract

The development of aggregation-induced emission (AIE) active material with high sensitivity, high quantum yield in aggregation state is of critical importance to high-tech applications as well as elucidation of the underlying mechanism and structure/behaviour relationships have cast our constant effort since the first discovery of the AIE phenomenon in 2001. Due to its fascinating properties and excellent perspective of the AIE materials in solid state, we have dedicated my all works towards the development of novel organic AIE materials and mechanistic understanding of the AIE phenomenon. For the AIE materials are widely used with the UV lamp as excitation, which is harmful to human being, the protocols of exciting the AIE material with free of UV light is one of the issue to be solved. Therefore, the main objectives of this thesis are: 1) mechanism study of AIE-active materials; 2) design and synthesize functional AIE-active materials; 3) develop and explore the electroluminescent material; 4) UV-free excitation protocols for AIE materials. The first proposed mechanism of AIE phenomenon is due to the main cause called restriction of intramolecular rotation (RIR) of the peripheral phenyl rings in the aggregate state. This hypothesis has been verified by experimental evidence and computational simulation. However we obtained some molecules is AIE-active those were not predicted with such properties. Following the phenomenon, the mechanism for AIE phenomenon is firstly recognized the twisting motion one of the vibration motions can also quench the excited state by non-radiative decay. The series of molecules with no freedom of rotation can behave AIE properties upon aggregation. A new class of dibenzothiophene containing tetraphenylethene (TPE) derivatives are designed and synthesized. Amino groups, methoxyl groups and methyl groups as electronic donor are introduced to enhance the electroluminescent (EL) properties. Being fabricated into the EL device, the high efficiency, low turn-on voltage and excellent brightness is achieved. With such solid state highly emissive AIE materials, we explored the protocol to imaging the latent prints of human grease. Within seconds, the fingerprints with even dispersed AIE powder are served to further digitalization processes. The AIE luminogens are mainly synthesized within organic family, but a series of copper (I) containing compound is recrystallized with AIE effect. To avoid the usage of UV excitation, one of the copper (I) compound exhibits the mechanoluminescence upon the crush, friction, stress and fracture, the other is emission-shifted after grinding upon UV excitation. With the chemical reaction energy transferring, a general chemiluminescent protocol for AIE materials is explored and developed

Date of Award	2013
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology