Jetting regimes of double-pulse laser-induced forward transfer

International audienceWe use the double-pulse laser-induced forward transfer (DP-LIFT) process, combining a quasi-continuous wave (QCW) and a femtosecond (fs) laser pulse to achieve jetting from a 1-µm thick copper film. The influence of the fs laser fluence on the dynamics of the liquid copper jetting is experimentally investigated by time-resolved shadowgraphy and theoretically analyzed with a simple energy balance model. Different jetting regimes are identified when varying the fs laser fluence. We demonstrate that the adjustment of this latter parameter while keeping all the others constant, allows accurate control of the diameter of the printed droplets from 1.9 µm to 6.0 µm. This leads us to a demonstration in which we print debris-free micro-pillars with an aspect ratio of 19 onto a silicon receiver substrate set as far as 60 µm away from the donor film

Tunable focal photopolymer lenses printed for the first time by laser-induced-forward transfer without a sacrificial layer

The fabrication of polymeric lens arrays on flexible surfaces for its use in wide-field visual systems is a challenge that is being addressed by using the Laser Induced Forward Transfer (LIFT) technique. The objective is to achieve polymer laser printing by improving both the overall printing quality and the manufacturing time of these lens matrices compared to other techniques. Another challenge when using tunable polymers is the customization of tunable focal lenses dynamically controlling their optical properties. In this work we address both aspects by using a tunable photopolymer thanks to liquid crystal molecules, such as H-PDLC.The work was supported by the “Ministerio de Ciencia e Innovación” of Spain (projects FIS2017-82919-R; PID2019-106601RB-I00), by the ‘‘Universidad de Alicante’’ (UATALENTO18-10; ACIE-20-10), and by Generalitat Valenciana (projects BEST/2021/021; IDIFEDER/2021/014, potential FEDER funding), and Marie Skłodowska Curie Postdoctoral Global Fellowship “FOCUSIS” grant agreement 844977

Liquid crystal doped photopolymer micro-droplets printed by a simple and clean laser-induced forward transfer process

We print a tunable photopolymer (photopolymer dispersed liquid crystal -PDLC), using the laser-induced direct transfer technique without absorber layer, which was a challenge for this technique given the low absorption and high viscosity of PDLC, and which had not been achieved so far to our knowledge. This makes the LIFT printing process faster and cleaner and achieves a high-quality printed droplet (aspheric profile and low roughness). A femtosecond laser was needed to reach sufficiently peak energies to induce nonlinear absorption and eject the polymer onto a substrate. Only a narrow energy window allows the material to be ejected without spattering.European Research Council (“FOCUSIS” grant agreement 844977); Universidad de Alicante (ACIE-20-10, UATALENTO18-10;); Ministerio de Ciencia e Innovación (PID2019-106601RB-I00, PID2021-123124OB-I00); Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital, Generalitat Valenciana (BEST/2021/021, IDIFEDER/2021/014, PROMETEO/2021/006)

Etude experimentale des comportements collectifs de bulles de cavitation generees par laser

SIGLEINIST T 71609 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

[INVITED] Laser-induced forward transfer: A high resolution additive manufacturing technology

International audienceAmong the additive manufacturing techniques, laser-induced forward transfer addresses the challenges of printing thin films in solid phase or small volume droplets in liquid phase with very high resolution. This paper reviews the physics of this process and explores the pros and cons of this technology versus other digital printing technologies. The main field of applications are printed electronics, organic electronics and tissue engineering, and the most promising short terms ones concern digital laser printing of sensors and conductive tracks. Future directions and emerging areas of interest are discussed such as printing solid from a liquid phase and 3D digital nanomanufacturing. (C) 2015 Elsevier Ltd. All rights reserved

Impression par laser (LIFT) de transistors organiques en films minces

L utilisation de composés organiques comme matériaux actifs représente la prochaine génération technologique. Ils permettent notamment un procédé de fabrication moins cher,de grands rendements de production ainsi que la capacité d employer des supports souples.Ce travail présente le développement d une technique de transfert reposant sur l ablation laser pour le dépôt fonctionnel de films minces localisé de matériaux organiques et inorganiques en phase liquide ou solide dans le but de fabriquer des transistors à films minces organiques (OTFT).La technique de dépôt est basée sur le LIFT (laser-induced forward transfer), dont le principe de fonctionnement implique que le matériau à transférer soit préalablement préparé sur un substrat transparent. Le matériau est irradié à travers ce dernier par une impulsion laser, déclenchant l ablation et l éjection de la matière du substrat. Le matériau éjecté est alors recueilli sur un substrat récepteur placé devant le film donneur. Par cette méthode, des structures précisément définies par la forme du faisceau laser peuvent être transférées.L irradiation directe de la matière à transférer n est pas admissible pour les composés sensibles, par conséquent, une modification de la technique a été introduite pour résoudre cette limitation. Cette modification implique l utilisation d une couche sacrificielle, qui est spécialement adaptée pour l ablation laser dans l ultraviolet. Cette couche sacrificielle est déposée entre le substrat et le matériel à transférer, son but est d absorber l impulsion laser, de se décomposer et de propulser le matériau sur le substrat receveur tout en le protégeant de l irradiation laser. Des matériaux métalliques et un matériau organique, le polymère triazene, ont été étudiés.Le processus de transfert a été étudié par ombroscopie résolue en temps. L analyse de la trajectoire du matériel éjecté ainsi que de l onde de choc créée par l ablation a été effectuée. Ces mesures nous ont permis de déterminer les conditions de transfert optimales pour chacun des matériaux étudiés et ont montré que la condition la plus favorable pour un transfert réussi est le proche contact dans le cas des matériaux en phase solide et quelques centaines de micromètres pour les matériaux en phase liquide.Enfin, la fabrication de transistors organiques opérationnels dans différentes configurations(bottom et top gate en configuration bottom et top contact) est démontrée. Les structures imprimées prouvent la capacité de la technique LIFT à transférer différents types de matériaux en maintenant leurs propriétés à un niveau significatif de performance. Le transfert d un ensemble multicouche OTFT est étudié. Les pixels transférés sont entièrement fonctionnels et présentent des propriétés compétitives à des dispositifs préparés par des techniques classiquesThe use of organic compounds as active materials represents the next generation oftechnology, enabling cheaper manufacturing process, high production and ability to useflexible substrates. This work presents the development of a transfer technique based onlaser ablation for the deposition of functional thin film of organic and inorganic materials,in liquid or solid phase, in order to achieve organic thin film transistors (OTFT).The deposition technique is based on the LIFT (laser-induced forward transfer), whoseworking principle involves a transparent substrate coated with the material to transfer. Thematerial is irradiated through the substrate by a laser pulse, which triggers the removaland ejection of the material from the substrate. The ejected material is then collected on asubstrate receiver placed in front the donor film. By this method, precise patterns definedby the shape of the laser beam can be transferred.Direct irradiation of the transfer material is not admissible for sensitive compounds,therefore a modification of the technique was introduced to solve this limitation. The modificationinvolves the use of a sacrificial layer, which is specially adapted for laser ablationin the ultraviolet. This sacrificial layer is deposited between the substrate and the materialto transfer, its purpose is to absorb the laser pulse, decomposes and propel the materialonto the receiver substrate while protecting it from laser irradiation. Metals and an organicmaterial, the triazene polymer, is studied.The transfer process has been studied by time-resolved shadowgraphic imaging technique.The trajectory analysis of the ejected material and of the shock wave created bythe ablation has been performed. These measures have enabled to determine the optimaltransfer conditions for each studied materials and have shown that the most favorablecondition for successful transfer is the close contact, in the case of materials solid phase,and few hundred micrometers for materials liquid phase.Finally, the fabrication of operating organic transistors in different configurations (bottomand top gate in bottom and top contact architectures) is demonstrated. The printedstructures reveals the ability of the LIFT technique to transfer different kinds of materialsmaintaining their properties at a significant level of performance. The transfer of a multilayersystem is also studied. Transferred pixels are fully functional and exhibit competitiveproperties face devices prepared by conventional techniquesAIX-MARSEILLE2-Bib.electronique (130559901) / SudocSudocFranceF

Laser Printing of Electronic Materials

International audienc

Laser cleaning of anodized aluminum in different surroundings

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Laser removal of the oxide layer on anodized aluminum

International audienc

Laser-induced forward transfer of polythiophene-based derivatives for fully polymeric thin film transistors

International audiencePolymeric thin-film transistors (pTFTs) have been fabricated by pulsed-laser printing of semiconductor and conductor polythiophene-based derivatives. Thin solid layers of semiconducting poly(3,3′″ didodecylquaterthiophene) (PQT-12) have been transferred by a laser-induced forward transfer (LIFT) technique on Si/SiO2 receiver substrates. Optimization of the transfer conditions and of the pixels morphologies has been realized. A marked improvement in the quality of the pixels has been observed, in terms of morphology and structure, by reducing the environmental pressure to 90 mbar during LIFT. Subsequently, poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) has also been laser-printed and used as source/drain electrodes in the transistor configuration. Functional polymeric transistors have been obtained with high field-effect mobility up to 2 × 10−2 cm2 V−1 s−1 together with current modulation of 104