Study on Excited State Kinetics and Optical Limiting Performance of Triphenylamine-Based Chalcone Derivatives: Effect of the Molecular π-Conjugated Structure

Abstract

Optical limiting (OL) is an important application of nonlinear optics. Summarizing the structure–property relationship of organic materials is an effective means to develop superior optical limiters. In this work, two triphenylamine-based chalcone derivatives T1 and T2 with different peripheral substituent groups were synthesized to study their transient kinetics and nonlinear optical (NLO) absorption performance. The transient absorption spectrum (TAS) of compounds T1 and T2 in solvents of varying polarities visualizes the intramolecular charge transfer (ICT) processes between the local excited state (LES) and the charge transfer state (CTS). Nanosecond Z-scan experiment and hole–electron analysis indicate that all compounds have excellent reverse saturated absorption (RSA) performance at 532 nm and T1 exhibits stronger RSA than T2 due to the stronger ICT performance of T1 caused by the halogen effect. Degenerate pump–probe experiment shows that the ESA of T2 at 532 nm is significantly enhanced by expanding the molecular π-conjugation. Under the premise of consistent linear transmittance (78%), compound T2 shows better OL performance than compound T1 at 532 nm in the nanosecond time domain. The OL thresholds of T1 and T2 are 3.72 and 0.72 J cm–2, respectively, which are better than those of the most reported OL materials. Our research shows that simple and common chalcone derivatives exhibit amazing NLO performance through a reasonable design.

Study of two-photon absorption and excited-state dynamics of coumarin derivatives: the effect of monomeric and dimeric structures

“…20 Targeted improvement of NLO absorption properties such as TPA and excited-state absorption (ESA) based on structure-property relationships is the key to the development of organic OL materials. 21 Numerous studies in the literature have suggested that the reverse saturable absorption (RSA) properties of organic materials can be improved by modulating the electron push-pull system and the molecular p-conjugated structure. [22][23][24][25] However, the majority of studies have not elucidated the effects of intramolecular charge transfer (ICT) and p-electron delocalization on TPA or ESA.…”

Synthesis, Photophysical, and Optical Limiting Properties of Twistacene-Functionalized Arenes

“…Among them, the smallest twistacene is 9,14-diphenyldibenzo­[ de , qr ]­tetracene, which can be regarded as an electron-rich motif. − In general, the sp-hybridized alkyne bond is a covalent bond linker, which can not only promote molecular coplanarity but also increase the π–π* transition within the molecules. , When the alkyne group is connected with the twistacene, the as-formed derivatives might possess excellent solubility in organic solvents, enhanced charge transfer, and broadband optical limiting ability. Although many derivatives resulting from such twistacenes with positive nonlinear optical responses have been prepared, − systematic examination of the effect of the connection mode of alkyne bonds on the nonlinear optical performance and absorption mechanism is unprecedented.…”