Long‐Term‐Stable Strong Second Harmonic Generation in Flexible DAST−PVDF Composite Films Realized by the Interface Interactions

Cheng, Xuewu; Xu, Xiangdong; Zhang, Mingang; Gu, Yang; Wang, Qu‐Quan; Qiu, Yun-Hang; Fan, Ting; Jiang, Yadong; Xu, Jimmy

doi:10.1002/admi.202100485

Cited by 6 publications

(19 citation statements)

References 47 publications

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“…The DAST nanoscale-thick films were systematically characterized by scanning electron microscopy (SEM, FEI INSPECT F), high-resolution transmission electron microscopy (HRTEM, JEM-2100F), X-ray diffraction (XRD, Philips X’PertProMPD), Fourier transform infrared spectroscopy (FTIR, PerkinElmer Spectrum 400), and UV–vis spectroscopy (Shimadzu UV-2600), respectively, as described in detail in ref . In TEM measurements, the DAST nanoscale-thick films deposited on the glass surfaces were first scraped off with a knife, and then, they were moved to the copper grids under guiding by a microscope, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…SHG signals were measured under irradiation by a Ti:sapphire laser operated at 5 mW, 800 nm, 100 fs, and 76 MHz, as described in detail in ref . The related setup is shown in Figure S1.…”

Section: Methodsmentioning

confidence: 99%

“…Various DAST-based optical nonlinear devices, such as light modulators, optical switches, frequency converters, and so forth, have been reported. − The DAST-related works can be traced back to that of Marder et al, reporting that the SHG intensity of DAST powders is orders of magnitude higher than that of urea powders at 1907 nm. Up to now, many attempts have been made to understand the SHG of DAST. ,, For example, Marinotto et al claimed that the polarity of the ITO surface can control the SHG signals from the DAST/PMMA films deposited on preheated ITO substrates . Forrest and co-workers investigated the SHG properties of the macroscopically ordered DAST film grown by low-pressure organic vapor-phase deposition .…”

Section: Introductionmentioning

confidence: 99%

“…Forrest and co-workers investigated the SHG properties of the macroscopically ordered DAST film grown by low-pressure organic vapor-phase deposition . Recently, we found that strong SHG signals can be measured from the annealed and poled DAST–PVDF composite films even after they have been exposed to an air atmosphere for 3 years due to the interface interactions between DAST and PVDF . Despite these achievements, one is still confused about how the strongest SHG intensity available from a DAST film can be realized.…”

Section: Introductionmentioning

confidence: 99%

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Engineering DAST Nanoscale-Thick Films for Giant and Isotropic Second Harmonic Generation: Implications for Bioimaging and Quantum Optics

Cheng

Zhang

et al. 2022

ACS Appl. Nano Mater.

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Second harmonic generation (SHG) is applied widely in frequency conversion, medical imaging, and quantum optics. 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) crystal, which is an outstanding organic nonlinear optical (NLO) material, has attracted considerable attention. To maximize its potential nonlinear properties, new degrees of freedomthe controls of the growth interface and temperature were explored to prepare DAST nanoscale-thick films with giant SHG in this work. Results reveal that a phase transition from a triclinic structure to a monoclinic structure in DAST nanoscale-thick films is initially and irreversibly induced at ∼120 °C. However, the ultrastrong SHG signal which is 4 orders of magnitude larger than those of both an unannealed DAST nanoscale-thick film and an inorganic potassium dihydrogen phosphate crystal can be measured from the DAST nanoscale-thick film deposited on the glass surface and annealed at 200 °C. This is attributed to a large second-order nonlinear susceptibility χ(2) of 7.24 nmV–1, high degree of structural ordering, formation of DAST single-crystal micro-platelets, and relaxation of the phase-matched condition in this case. Interestingly, the isotropic giant SHG response can be measured from such a DAST single-crystal nanoscale-thick film, attributed to the synergistic effects of the anisotropic DAST single-crystal micro-platelets with various preferential orientations distributed uniformly on the substrate surface and the interface interactions between DAST and the glass substrate. These findings shed light on the engineering of DAST nanostructures for significantly enhancing the SHG response, and particularly, they also pave an efficient way toward seeking the strongest nonlinear optical performances from DAST and other NLO organic materials for bioimaging and quantum optics.

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Section: Methodsmentioning

confidence: 99%

“…SHG signals were measured under irradiation by a Ti:sapphire laser operated at 5 mW, 800 nm, 100 fs, and 76 MHz, as described in detail in ref . The related setup is shown in Figure S1.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Engineering DAST Nanoscale-Thick Films for Giant and Isotropic Second Harmonic Generation: Implications for Bioimaging and Quantum Optics

Cheng

Zhang

et al. 2022

ACS Appl. Nano Mater.

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“…Substantial progress has been made in the development of crystalline thin films. [18][19][20] However, these films have disadvantages such as unstable morphology and thermodynamic state, and a large number of grain boundaries, which limit their further applications. Long-range ordered single-crystal materials can compensate for these defects and maximize the inherent potential of the material.…”

Section: Introductionmentioning

confidence: 99%

Strong In‐Plane Anisotropy and Giant Second Harmonic Generation Response of Organic Single‐Crystalline Microwire Arrays

Guo

Zhao

Dong

et al. 2022

Advanced Optical Materials

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Organic nonlinear optical (NLO) crystals play an indispensable role in high‐performance photonic devices due to their large nonlinear coefficient, fast response time, and low dielectric constant. However, in contrast to the strides of bulk crystals, researches on the next generation of nanophotonic devices are ignored to some extent. One of the bottlenecks is the controllable manufacturing and patterning of high‐quality organic NLO crystals with the nanometer‐scale thickness. Herein, a confined assembly method for fabricating the microwire arrays of organic NLO crystal OH1 and DAT2 with precise position, flat morphology, high crystallinity, and consistent crystallographic orientation is reported. Two strong NLO effects observed in the experiments are comprehensively studied, including second harmonic generation (SHG) and two‐photon excited fluorescence. Furthermore, it is demonstrated that the anisotropic SHG effect depends on both the polarization of incident light and the crystallographic orientation of microwire arrays. Microwire arrays can exhibit large in‐plane anisotropy with the polarization ratio up to 0.95 and second‐order nonlinear coefficient up to 55.1 pm V−1. This work provides new insights into the potential applications of organic NLO crystals in integrated optical devices.

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Ultra‐High Nonlinear Saturable Absorption Responses and Ultra‐Fast Carrier Dynamics of Organic DAST

Zhang

et al. 2022

Advanced Optical Materials

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organic SA materials have been identified and investigated in the past decades. [4][5][6][7][8][9] Nevertheless, most inorganic SA materials, such as graphene (G), [6] black phosphorus (BP), [7] transition metal sulfides, [4,8] and topological insulators, [9] still suffer from some inherent limitations. For example, the saturation modulation depth of a monolayer G is only 0.5−1.8% in the wavelength range of 800−1500 nm, unsuitable for stable mode-locking. [10] The oxidation in ambient air of BP has been an impediment to its commercialization and industrialization. [11] The bulk transition metal sulfides are unable to generate ultra-short laser pulses, due to their long intraband electron relaxation times, at the scale of picosecond. [10,12] The extremely low saturation intensities of topological insulators at the scale of W cm −2 hinder their practical applications in continuous-wave modelocking. [10,13] Particularly, these aforementioned inorganic SA materials generally lack a controllable, reproducible, high-yield, and low-cost preparation process. [10] In contrast, organic SA materials have shown the advantages of good flexibility, reproducible preparation processes, diverse molecular design possibilities, and fast NLO responses. [14][15][16] However, the nonlinear SA performances of most organic SA materials are generally lower than those of inorganic SA materials, limiting practical applications of the former in the optoelectronic devices. [16] Moreover, the transient carrier dynamics of most organic SA materials, important for Third-order nonlinear optical (NLO) absorption properties and ultra-fast carrier dynamics of organic 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) at the wavelength of 520 nm are investigated by femtosecond open-aperture Z-scan technique and transient absorption spectroscopy, respectively. Z-scan measurements indicate that DAST solution exhibits ultra-high nonlinear saturable absorption (SA) responses with a figure of merit of 4.57 × 10 −13 esu cm and a saturation strength of 3.20 GW cm −2 , far superior to those of the most known 2D SA materials under similar excitations. Transient absorption results reveal that the outstanding SA performances of the solution-phase DAST are rooted in ultra-fast ground-state bleaching based on the Pauli blocking effect. The subsequent excited state carrier relaxation processes are dominated by rapid intraband carrier cooling and defect-assisted interband Auger recombination. Moreover, high-quality DAST−polyvinyl alcohol composite films prepared by solution casting exhibit similar ultra-high SA responses and reliable long-term stability without any degradation of their SA responses even after exposure to air moisture for 100 days. These findings establish an experimental and theoretical foundation for the development of high-performance ultra-fast optoelectronic devices based on organic NLO materials in the future.

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Long‐Term‐Stable Strong Second Harmonic Generation in Flexible DAST−PVDF Composite Films Realized by the Interface Interactions

Cited by 6 publications

References 47 publications

Engineering DAST Nanoscale-Thick Films for Giant and Isotropic Second Harmonic Generation: Implications for Bioimaging and Quantum Optics

Engineering DAST Nanoscale-Thick Films for Giant and Isotropic Second Harmonic Generation: Implications for Bioimaging and Quantum Optics

Strong In‐Plane Anisotropy and Giant Second Harmonic Generation Response of Organic Single‐Crystalline Microwire Arrays

Ultra‐High Nonlinear Saturable Absorption Responses and Ultra‐Fast Carrier Dynamics of Organic DAST

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