Femtosecond Laser-induced Forward Transfer Research Articles

High‐Resolution Full‐Color Quantum Dots Patterning for Display Applications Based on Femtosecond Laser‐induced Forward Transfer

AbstractColloidal quantum dots (QDs) have been widely studied in display panels due to their near‐unity fluorescence quantum yield and the ability to tune colors across a wide gamut. However, the challenge persists in creating full‐color QD arrays with the necessary precision for high‐resolution display applications in the next generation. This paper introduces a femtosecond laser‐induced forward transfer (FsLIFT) technology that integrates deposition pattern and alignment in a single transfer step. This development enables the fabrication of high‐resolution full‐color QD films. The ability of FsLIFT to precisely locate red, green, and blue QDs in a designated position allows to obtain arbitrarily shaped full‐color patterns and pixel arrays with a resolution of 1.78 µm. In addition, the potential for optoelectronic devices is ensured by the preserved photophysical properties, high smoothness, and continuity of the transferred QD films. Consequently, the light‐emitting diodes (LEDs) are successfully fabricated based on the transferred QD films. This study expects that the introduced straightforward patterning technology, offering high freedom, precision, and repeatability, will contribute to advancing the development of full‐color high‐resolution displays based on QDs.

Full‐Color High‐Capacity Dynamic Information Encryption Based on Femtosecond Laser‐Induced Forward Transfer

AbstractThe development of dynamic 3D codes is widely studied, especially for smart information protection and advanced dynamic information encryption. However, it is challenging to fabricate information carriers with full color, dynamic properties under external stimuli, and high capacity, which restricts their applications. Here, microsized dynamic full color fluorescent 3D codes are successfully fabricated using the multilayer‐independent femtosecond laser‐induced forward transfer (FsLIFT) technology, which achieves simultaneous high‐resolution transferring and patterning. The combination and excitation of multilayered quantum dots film with different colors and patterns ensure dynamic information transformation of the 3D codes. Due to the high spatial resolution of the FsLIFT, the minimum line width of the patterns can reach 1.78 µm, which ensures a high capacity for encoding. In addition, the decoding process of the microsized dynamic fluorescent 3D codes only requires smartphones, microscope patches, and portable light sources. Finally, the facile fabrication and decoding process as well as the customizable patterning abilities demonstrate the practical application potential for the advanced dynamic coding.

High-Resolution Patterning of Perovskite Quantum Dots via Femtosecond Laser-Induced Forward Transfer

High-resolution patterning of perovskite quantum dots (PQDs) is of significant importance for satisfying various practical applications, including high-resolution displays and image sensing. However, due to the limitation of the instability of PQDs, the existing patterning strategy always involves chemical reagent treatment or mask contact that is not suitable for PQDs. Therefore, it is still a challenge to fabricate high-resolution full-color PQD arrays. Here, we present a femtosecond laser-induced forward transfer (FsLIFT) technology, which enables the programmable fabrication of high-resolution full-color PQD arrays and arbitrary micropatterns. The FsLIFT process integrates transfer, deposition, patterning, and alignment in one step without involving a mask and chemical reagent treatment, guaranteeing the preservation of the photophysical properties of PQDs. A full-color PQD array with a high resolution of 2 μm has been successfully achieved. We anticipate that our facile and flexible FsLIFT technology can facilitate the development of diverse practical applications based on patterned PQDs.

Chameleon-inspired design of dynamic patterns based on femtosecond laser-induced forward transfer

Chameleon can display variable body color/patterns under environmental stimulation via bioelectricity-controlled three layers of pigment cells and photonic crystals in the chameleon's skin. Inspired by color variation of chameleon, numerous “smart skins” have been achieved successfully, which possess great potential for optical information record and security. However, it remains challenging to produce full color dynamic fluorescent patterns with higher precision and flexibility to improve information capacity and anti-counterfeiting property. In this work, the micro-sized full color dynamic fluorescent patterns were successfully achieved by multiple transferring different colored quantum dots (QDs) from the carrier substrates to the receiving substrate via femtosecond laser-induced forward transfer (FsLIFT) technology using the chameleon skin as a prototype. The ability to dynamically display by facilely controlling the excitations is demonstrated, ensuring the information transformation function as chameleon skin. The resulting dynamic fluorescent patterns provide dual biomimetic of chameleon skin morphology and function. To illustrate the promising practical applications, flexible information encryption and information decryption relying on portable devices based on the fabricated dynamic fluorescent patterns have been achieved. It is anticipated that this bioinspired strategy is universal and promising for fabricating on-demand fluorescent dynamic patterns.

Hybrid superhydrophilic\u2013superhydrophobic micro/nanostructures fabricated by femtosecond laser-induced forward transfer for sub-femtomolar Raman detection

Raman spectroscopy plays a crucial role in biochemical analysis. Recently, superhydrophobic surface-enhanced Raman scattering (SERS) substrates have enhanced detection limits by concentrating target molecules into small areas. However, due to the wet transition phenomenon, further reduction of the droplet contact area is prevented, and the detection limit is restricted. This paper proposes a simple method involving femtosecond laser-induced forward transfer for preparing a hybrid superhydrophilic–superhydrophobic SERS (HS-SERS) substrate by introducing a superhydrophilic pattern to promote the target molecules to concentrate on it for ultratrace detection. Furthermore, the HS-SERS substrate is heated to promote a smaller concentrated area. The water vapor film formed by the contact of the solution with the substrate overcomes droplet collapse, and the target molecules are completely concentrated into the superhydrophilic region without loss during evaporation. Finally, the concentrated region is successfully reduced, and the detection limit is enhanced. The HS-SERS substrate achieved a final contact area of 0.013 mm2, a 12.1-fold decrease from the unheated case. The reduction of the contact area led to a detection limit concentration as low as 10−16 M for a Rhodamine 6G solution. In addition, the HS-SERS substrate accurately controlled the size of the concentrated areas through the superhydrophilic pattern, which can be attributed to the favorable repeatability of the droplet concentration results. In addition, the preparation method is flexible and has the potential for fluid mixing, fluid transport, and biochemical sensors, etc.

Fabrication of Regularly Arranged Chalcopyrite Micro Solar Cells via Femtosecond Laser-Induced Forward Transfer for Concentrator Application

A laser-based bottom-up technique for the fabrication of Cu(In,Ga)Se2 (CIGSe) micro solar cells is presented. We use femtosecond laser-induced forward transfer (LIFT) to transport a metallic precursor composed of copper, indium, and gallium onto a molybdenum back contact layer on a glass substrate. A CIGSe absorber forms by subsequent selenization. An array of micro absorbers with defined spacing is fabricated to solar cells and characterized under concentrated light illumination. The solar cell array exhibited a conversion efficiency of 1.4‰ at 1 sun as well as a significant efficiency enhancement of 68% rel. under 20-fold concentration. This work demonstrates the possibility of directly grown micrometer-sized solar cells based on chalcogenide absorber layers, enabling effective material usage.

飞秒激光前向转移诱导产生金属纳米结构薄膜

飞秒激光前向转移诱导产生金属纳米结构薄膜

Femtosecond Laser High Precision Fabrication for Novel Applications

Background: Femtosecond laser provides a versatile tool for microand nanofabrication, such as periodic surface structures with a periodicity much less than the wavelength, microfluidic channels for biological uses, photonic metamaterials and optical integrated circuits for quantum applications. These facts prove that fabrication methods based on femtosecond laser have provided convenience for novel applications in the fields of high precision fabrication, experimental quantum physics, functional materials, etc. Methods: We focus on the novel applications of the femtosecond laser high precision fabrication, such as quantum integrated circuits, biological and medical devices, multifunctional surfaces and functional periodic arrays. These applications are mostly undertook this 5 years, especially the quantum integrated circuits which were studied since 2013. Moreover, case studies were shown to illustrate the representative results and study methods. Results: We have reviewed 128 papers that are associated with the novel applications and case studies. Approximate 50% papers introduced the novel applications in the fields of quantum integrated circuits, biological and medical devices, multifunctional surfaces and functional periodic arrays. Other papers presented illustrated the case studies including femtosecond laser-induced forward transfer, characterization of femtosecond laser-induced periodic surface structures and results led by femtosecond vortex beam generated by a q-plate. Conclusion: The applications of the technology of the femtosecond laser direct writing waveguides in the fields of integrated quantum optics, photonic metamaterials, biological and medical circuits will surely pave a new way to fabricate full-size quantum computer and provide enormous kinds of biomimetic and medical finer devices. These state-of-the-art microdevices will provide much more convenience than before and even probably overturn the structure of the modern industry society. With the development of the relative technologies, femtosecond laser will prominently enhance the level of the fabrication in particular fields. Keywords: Direct laser writing, femtosecond laser, integrated quantum circuits, LIFT, LIPSS, microfluidic channels, optical vortex beam, precision fabrication.

Micro-patterning of Indium thin film for generation of micron and submicron particles using femtosecond laser-induced forward transfer

AbstractThis paper reports on micro-pattering of Indium thin film (donor substrate) using a higher deposition dose than previously reported. The threshold deposition dose required for micro-patterning was measured. Ejected material from the micro-patterned thin film was deposited onto an accepter substrate kept in close proximity; it clearly shows deposition of micron and submicron particles of Indium. Moreover, a clean line like structure was deposited onto the accepter substrate when the accepter substrate was moved with the same velocity as that of the donor substrate.

Micron-scale copper wires printed using femtosecond laser-induced forward transfer with automated donor replenishment

We demonstrate the use of laser-induced forward transfer (LIFT) in combination with a novel donor replenishment scheme to print continuous copper wires. Wires of mm length, a few microns wide and submicron in height have been printed using a 800 nm, 1 kHz repetition rate, 150 fs pulsed laser. A 120 nm thick copper donor was used along with laser pulse energy densities of 0.16-0.21 J cm−2 to print overlapping few-micron sized pads to form the millimeter long wires. The wires have a measured resistivity of 17 ± 4 times that of bulk copper.

Fabrication of three-dimensional plasmonic cavity by femtosecond laser-induced forward transfer

We fabricated a three-dimensional five-layered plasmonic resonant cavity by low-cost, efficient and high-throughput femtosecond laser-induced forward transfer (fs-LIFT) technique. The fabricated cavity was characterized by optical measurements, showing two different cavity modes within the measured wavelength region which is in good agreement with numerical simulations. The mode volume corresponding to each resonance is found to be squeezed over 10(4) smaller than the cube of incident wavelength. This property may facilitate many applications in integrated optics, optical nonlinearities, and luminescence enhancement, etc.

Micro-Deposition of the Film Material Using Femtosecond Laser Pulse

The femtosecond laser-induced forward transfer of the aluminum film had been studied experimentally by single-shot laser pulse (pulse duration 148fs, central wavelength 775nm). With the help of the atomic force microscope and scanning electron microscope, the dependence of morphology and dimension of deposited dots on irradiated laser pulse energy were investigated. It was revealed the threshold fluence for transfer was ~6.3 J/cm2 for the aluminum thin film with a thickness of ~500 nm. It also was presented the micro patterns of the aluminum film on a quartz substrate fabricated using the femtosecond laser-induced forward transfer .

Fabrication of plasmonic devices using femtosecond laser-induced forward transfer technique

Using femtosecond laser-induced forward transfer techniques we have fabricated gold dots and nanoparticles on glass substrates, as well as nanobumps on gold thin film. The surface morphologies of these structures with different laser fluences and film thicknesses are investigated. We also study the focusing and defocusing properties of the nanofence—an arranged nanobump pattern—by the total-internal reflection microscope. Observations reveal that surface plasmon waves can be highly directed and focused via this nanofence pattern. Results are in good agreement with the simulation results using the finite-element method and demonstrate the potential applications of these nanophotonic devices. Furthermore, we utilize high laser energy to fabricate plasmonic waveguides, and also succeed in transferring the waveguides to another substrate. The attenuation rates of the light propagating in the waveguides are observed to achieve 0.31 dB μm−1 and 0.48 dB μm−1 on the target and receiver sides, respectively.

Time-resolved shadowgraph imaging of femtosecond laser-induced forward transfer of solid materials

The transfer of solid phase material by femtosecond laser-induced forward transfer (LIFT) at atmospheric pressure by a time-resolved shadowgraph technique is studied. The influence of laser fluence on transfer of material in solid, fragmented and molten state is investigated during femtosecond LIFT of initially solid layers of thermoelectric bismuth selenide (Bi2Se3), piezoelectric lead zirconate titanate (PZT) and magnetostrictive Terfenol-D. We report ejection velocities of ∼48m/s and ∼34m/s for intact transfer of ∼1.1μm thick Bi2Se3 and ∼1.8μm thick PZT respectively, and of ∼140m/s for ∼0.5μm thick Terfenol-D. During intact transfer, contrary to what has been reported so far, no shock wave above the substrate surface was observed.

Top down fabrication of organic nanocrystals by femtosecond laser induced transfer method

We present the preparation of nanometer-size organic crystals using femtosecond laser induced forward transfer (Fs-LIFT) method. 1,4-Bis(4-methylstyryl)benzene (BSB-Me) nanocrystals are directly deposited on the substrate to form a nanocrystal film. Size and morphology as functions of applied laser fluence are investigated. We show that monodispersed organic nanoparticles with size varying from 40 nm to 300 nm could be obtained by careful adjustment of the experimental conditions. The produced nanoparticles exhibit well defined shapes, such as cube and tetrahedron with rather sharp edges. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. The organic nanoparticles are demonstrated single crystalline, and FTIR spectra before and after the Fs-LIFT process shows that no significant chemical decomposition occurs during the process.

Influence of optical standing waves on the femtosecond laser-induced forward transfer of transparent thin films

The effects of the formation of an optical standing wave during femtosecond laser-induced forward transfer of transparent films is analyzed using a numerical interference model. The dependence of the intensity distribution on a number of easily controllable experimental parameters is investigated. Results of the model are compared to experimental studies of the transfer of gadolinium gallium oxide (GdGaO) with a polymer sacrificial layer. The model allows us to explain the observed variation in deposit morphology with the size of the air gap, and why forward transfer of the GdGaO was possible below the ablation thresholds of polymer and oxide.