Aggregation Induced Emission and Nonlinear Optical Properties of an Intramolecular Charge-Transfer Compound.

Songhua Chen,Rui Luo,Xinyue Li,Shanshan Fu,Meiyun He,Jialiang Xu

doi:10.3390/ma14081909

Songhua Chen, Rui Luo + Show 4 more

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https://doi.org/10.3390/ma14081909

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Abstract

Intramolecular charge transfer (ICT) compounds have attracted wide attention for their potential applications in optoelectronic materials and devices such as fluorescent sensors, dye-sensitized solar cells, organic light emitting diodes and nonlinear optics. In this work, we have synthesized a new ICT compound, dimethyl-[4-(7-nitro-benzo[1,2,5]thiadiazol-4-yl)-phenyl]-amine (BTN), and have fabricated it into low dimensional micro/nano structures with well-defined morphologies. These self-assembled nanostructures exhibit high efficiency solid state fluorescence via an aggregation induced emission mechanism, which overcomes the defect of fluorescence quenching caused by aggregation in the solid state of traditional luminescent materials. We also explored and studied the nonlinear optical properties of this material through the Z-scan method, and found that this material exhibits large third-order nonlinear absorption and refraction coefficients, which promises applications of the materials in the fields of nonlinear optics and optoelectronics.

Highlights

When conventional organic fluorescent materials engage in π -stacking, the luminescence is partially or completely quenched [1]
Many mechanisms, such as the essential structure flattening, restriction of intramolecular motions (RIM), restriction of intramolecular vibrations (RIV), restriction of intramolecular rotations (RIR), twisted intramolecular charge transfer (TICT), J-aggregation formation (JAF), excited state intramolecular proton transfer (ESIPT), excited state intramolecular charge transfer (ESICT) and other theories [2,4,5,6] have been proposed as the explanation of this phenomenon
It can be estimated that the n2 value of the nonlinear refractive index coefficient of BTN is 3.4 × 10−18 m2 /W. These results show that BTN has high third-order nonlinear absorption and nonlinear refraction coefficients, which promise great potential of these material for applications in well-defined nonlinear optical materials

Summary

Introduction

When conventional organic fluorescent materials engage in π -stacking, the luminescence is partially or completely quenched [1]. Such aggregation leads to aggregation-caused quenching (ACQ), mainly due to the strong π-stacking among molecules and the formation of excimer complexes. AIE molecules, in contrast to conventional dyes, can emit light efficiently in the solid state, which fundamentally solves the problem of ACQ and makes fluorescent materials rich, extended and developed [3]. Many AIE materials have been designed and synthesized for wide applications in the fields such as organic light-emitting diodes, sensing and biological imaging [8,9]

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