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The development of thin-film photovoltaics has emerged as a promising solution to the global energy crisis within the field of solar cell technology. However, transitioning from laboratory scale to large-area solar cells requires precise and high-quality scribes to achieve the required voltage and reduce ohmic losses. Laser scribing has shown great potential in preserving efficiency by minimizing the drop in geometrical fill factor, resistive losses, and shunt formation. However, due to the laser induced photothermal effects, various defects can initiate and impact the quality of scribed grooves and weaken the module’s efficiency. In this regard, much research has been conducted to analyze the geometrical fill factor, surface integrity, and electrical performance of the laser scribes to reach higher power conversion efficiencies. This comprehensive review of laser scribing of photovoltaic solar thin films pivots on scribe quality and analyzes the critical factors and challenges affecting the efficiency and reliability of the scribing process. This review also covers the latest developments in using laser systems, parameters, and techniques for patterning various types of solar thin films to identify the optimized laser ablation condition. Furthermore, potential research directions for future investigations at improving the quality and performance of thin film laser scribing are suggested. 

Owing to the opaque nature of the laminated structures, traditional high-speed optical camera cannot be used to detect the dynamic process of sub-surface deformation. In this article, we report a study of using high speed X-ray imaging to study the high strain rate deformation in laminated Al structures. We used a Kolsky bar apparatus to apply dynamic compression and a high-speed synchrotron X-ray phase contrast imaging (PCI) setup to conduct the in situ X-ray imaging study. The in situ X-ray imaging captures the shock wave propagation in the laminated structures. After shock compression, we characterized the microstructures by using transmission electron microscopy (TEM), which demonstrates an increase of dislocation density. The micro-pillar compression tests show that the yield strength at 0.2% offset of laminated Al-graphene composite has a significant increase of 67%, from 30 to 50 MPa, compared to laminate Al after shock loading. 

The concept for fabrication of waveguides by an in‐volume laser direct writing in single‐crystal silicon is explored using a nanosecond pulse laser. The key innovation of this technology relies on the generation of amorphous silicon, which has a higher refractive index than that of crystalline silicon. Herein, transmission electron microscopy (TEM) together with selected area electron diffraction (SAED) and high‐resolution TEM (HRTEM) characterizations are used to better understand the microstructural evolutions. TEM images reveal the core‐shell structures, while SAED patterns and HRTEM directly observe the presence of amorphous silicon in the core surrounded by a crystalline silicon shell. With a lower laser scanning speed, a higher density of defects yet less amorphous silicon is formed by laser direct writing.

 

Abstract With the invention of chirped pulse amplification for lasers in the mid-1980s, high power ultrafast lasers entered into the world as a disruptive tool, with potential impact on a broad range of application areas. Since then, ultrafast lasers have revolutionized laser–matter interaction and unleashed their potential applications in manufacturing processes. With unprecedented short pulse duration and high laser intensity, focused optical energy can be delivered to precisely define material locations on a time scale much faster than thermal diffusion to the surrounding area. This unique characteristic has fundamentally changed the way laser interacts with matter and enabled numerous manufacturing innovations over the past few decades. In this paper, an overview of ultrafast laser technology with an emphasis on femtosecond laser is provided first, including its development, type, working principle, and characteristics. Then, ultrafast laser applications in manufacturing processes are reviewed, with a focus on micro/nanomachining, surface structuring, thin film scribing, machining in bulk of materials, additive manufacturing, bio manufacturing, super high resolution machining, and numerical simulation. Both fundamental studies and process development are covered in this review. Insights gained on ultrafast laser interaction with matter through both theoretical and numerical researches are summarized. Manufacturing process innovations targeting various application areas are described. Industrial applications of ultrafast laser-based manufacturing processes are illustrated. Finally, future research directions in ultrafast laser-based manufacturing processes are discussed.