Microfabrication of electroluminescent polymer for devices construction

Estevam-Alves, R.; Ferreira, P. H. D.; Almeida, G. F. B.; Sousa, W. S.

doi:10.1016/j.apsusc.2014.07.074

Cited by 6 publications

(7 citation statements)

References 37 publications

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“…At the same time, semiconductor polymers are fascinating materials for studying nonlinear optical effects such as two-photon absorption (2PA). Organic materials for 2PA are interesting for applications in 3D micro-fabrication and micromachining [ 7 , 8 , 9 , 10 ], 3D data storage [ 11 , 12 ], optical power limiting [ 13 , 14 ], two-photon induced photopolymerization [ 15 ], two-photon pumped laser [ 16 ], and so on. The key feature for such applications is the quadratic dependence of the 2PA process on the excitation irradiance, which provides spatial confinement of excitation [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Two-Photon Absorption Spectroscopy of Poly(fluorene) Derivatives Containing Benzoselenadiazole and Benzothiadiazole

et al. 2017

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We have investigated the molecular structure and two-photon absorption (2PA) properties relationship of two push–pull poly(fluorene) derivatives containing benzoselenadiazole and benzothiadiazole units. For that, we have used the femtosecond wavelength-tunable Z-scan technique with a low repetition rate (1 kHz) and an energy per pulse on the order of nJ. Our results show that both 2PA spectra present a strong 2PA (around 600 GM (1 GM = 1 × 10−50 cm4·s·photon−1)) band at around 720 nm (transition energy 3.45 eV) ascribed to the strongly 2PA-allowed 1Ag-like → mAg-like transition, characteristic of poly(fluorene) derivatives. Another 2PA band related to the intramolecular charge transfer was also observed at around 900 nm (transition energy 2.75 eV). In both 2PA bands, we found higher 2PA cross-section values for the poly(fluorene) containing benzothiadiazole unit. This outcome was explained through the higher charge redistribution at the excited state caused by the benzothiadiazole group as compared to the benzoselenadiazole and confirmed by means of solvatochromic Stokes shift measurements. To shed more light on these results, we employed the sum-over-states approach within the two-energy level model to estimate the maximum permanent dipole moment change related to the intramolecular charge transfer transition.

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Section: Introductionmentioning

confidence: 99%

Femtosecond Two-Photon Absorption Spectroscopy of Poly(fluorene) Derivatives Containing Benzoselenadiazole and Benzothiadiazole

et al. 2017

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“…When energy densities above 101 mJ/cm 2 are used, the removal of the chitosan from the sample is observed, as illustrated in the AFM images. For energy densities below 62 mJ/cm 2 , no removal of material was observed from the sample surface (data not shown), indicating that the energy density threshold for chitosan ablation is at about 62 mJ/cm 2 [ 32 , 33 ]. Therefore, the micromachined lines observed in Figure 1 a for an energy density of 62 mJ/cm 2 are only related to material changes and not removal.…”

Section: Resultsmentioning

confidence: 99%

Femtosecond Laser Patterning of the Biopolymer Chitosan for Biofilm Formation

Estevam-Alves

Ferreira

Coatrini

et al. 2016

IJMS

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Controlling microbial growth is crucial for many biomedical, pharmaceutical and food industry applications. In this paper, we used a femtosecond laser to microstructure the surface of chitosan, a biocompatible polymer that has been explored for applications ranging from antimicrobial action to drug delivery. The influence of energy density on the features produced on chitosan was investigated by optical and atomic force microscopies. An increase in the hydrophilic character of the chitosan surface was attained upon laser micromachining. Patterned chitosan films were used to observe Staphylococcus aureus (ATCC 25923) biofilm formation, revealing an increase in the biofilm formation in the structured regions. Our results indicate that fs-laser micromachining is an attractive option to pattern biocompatible surfaces, and to investigate basic aspects of the relationship between surface topography and bacterial adhesion.

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“…Taking advantage of these features, fs-laser micromachining of MEH-PPV films has been carried out by researchers, as reported by [56]. In that study, the authors produced 14 μm thick MEH-PPV films by casting a solution of this polymer on a The domain of experimental parameters along with the understanding of local refractive index change has enabled the fabrication of waveguides in PMMA with a virtually symmetric fundamental mode and a propagation loss of 0.5 dB/cm [52].…”

Section: Fluorescent Polymeric Structuresmentioning

confidence: 99%

“…Taking advantage of these features, fs-laser micromachining of MEH-PPV films has been carried out by researchers, as reported by [56]. In that study, the authors produced 14 µm thick MEH-PPV films by casting a solution of this polymer on a Teflon recipient over a glass substrate.…”

Section: Fluorescent Polymeric Structuresmentioning

confidence: 99%

Ultrafast Laser Pulses for Structuring Materials at Micro/Nano Scale: From Waveguides to Superhydrophobic Surfaces

Corrêa

Almeida

et al. 2017

Photonics

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Abstract:The current demand for fabricating optical and photonic devices displaying high performance, using low-cost and time-saving methods, prompts femtosecond (fs)-laser processing as a promising methodology. High and low repetition femtosecond lasers enable surface and/or bulk modification of distinct materials, which can be used for applications ranging from optical waveguides to superhydrophobic surfaces. Herein, some fundamental aspects of fs-laser processing of materials, as well as the basics of their most common experimental apparatuses, are introduced. A survey of results on polymer fs-laser processing, resulting in 3D waveguides, electroluminescent structures and active hybrid-microstructures for luminescence or biological microenvironments is presented. Similarly, results of fs-laser processing on glasses, gold and silicon to produce waveguides containing metallic nanoparticles, analytical chemical sensors and surface with modified features, respectively, are also described. The complexity of fs-laser micromachining involves precise control of material properties, pushing ultrafast laser processing as an advanced technique for micro/nano devices.

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Microfabrication of electroluminescent polymer for devices construction

Cited by 6 publications

References 37 publications

Femtosecond Two-Photon Absorption Spectroscopy of Poly(fluorene) Derivatives Containing Benzoselenadiazole and Benzothiadiazole

Femtosecond Two-Photon Absorption Spectroscopy of Poly(fluorene) Derivatives Containing Benzoselenadiazole and Benzothiadiazole

Femtosecond Laser Patterning of the Biopolymer Chitosan for Biofilm Formation

Ultrafast Laser Pulses for Structuring Materials at Micro/Nano Scale: From Waveguides to Superhydrophobic Surfaces

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