Aggregation-induced emission materials for nonlinear optics

Abstract

Aggregation-induced emission (AIE) is a vital photophysical phenomenon that the luminogens in the concentrated or aggregated cases will engender the dramatically boosted emission in comparison with the dispersive states. Given this extraordinary emitting capacity exactly resolves the aggregation-caused quenching (ACQ) situations residing in the traditional luminophores, the booming AIE luminogens have drawn tremendous interest owing to their advanced performances and colossal potential applications in various areas. Further exploitations of AIE molecules also drive the research interests in the midst of these AIE materials toward the nonlinear optical (NLO) regime. The combination of AIE and NLO effects have nurtured some unforeseen properties of AIE materials and extended their application spheres. Therefore, some NLO-active AIE materials have been wielded in many crucial applications, for example, optical limiting, laser, bioimaging, and photodynamic therapy. Meanwhile, the impacts of aggregate on the NLO effect also deserve deep considerations and pursuits, and the modifications of aggregates promise an easy, efficient, and prompt avenue to tune the NLO properties of materials. The recent achievements and progress in the NLO properties of AIE materials have been summarized in this review. The second-order and third-order NLOs of the AIE materials have been introduced and their correlative applications have been discussed.