Direct Laser Patterning of Copper-Graphene Composite Structures for Flexible Electronics

这项研究计划将通过深入了解激光加工条件与铜纳米颗粒和/或铜-石墨烯结的界面结构以及复合结构的电/热性能之间的关系，并最终了解原型柔性电子学的性能，专注于在各种电子应用的衬底上快速制备铜-石墨烯(Cu-Gr)复合结构的直接激光写入工艺。 这项研究的三个目标是：(I)开发一步直写工艺，用于在不同衬底上快速图案化铜-Gr复合材料；(Ii)研究激光诱导热产生、铜纳米颗粒的形成和连接、聚合物快速热解和Gr结构生长过程，特别是将激光热产生与铜-铜和铜-Gr界面的微结构和缺陷与其导电性联系起来；(Iii)利用所写的铜和/或铜-Gr复合结构的不同的电和热性质，设计和制造柔性电子学原型，并研究其与微结构和环境刺激相关的功能和性能。 这项研究将使用铜离子(如Cu2和铜)和水溶性聚合物(如聚乙烯吡咯烷酮-PVP、聚乙二醇-聚乙二醇单宁)墨水在经过适当表面处理后涂覆基材(塑料、硅、纸)的表面。激光写入参数将包括激光功率、扫描速度、波长等。先进的分析技术将用于研究铜和Gr的形成以及铜颗粒或铜到Gr界面的缺陷。将对所写结构的电/热传导性和机械性能进行表征。模拟将被用来理解在短时间内激光照射下Gr在铜表面的生长情况。所制备的纯铜和铜-Gr复合结构将被集成到柔性衬底上的功能器件中，如气体/应变传感器和光电探测器，以测试其性能。 这项研究计划的成功实施将使人们对材料科学中激光-材料相互作用和微结构-性能关联的科学现象有一个基本的了解，特别是在激光热产生、金属铜的熔化和凝固、连接过程中的原子扩散、激光转化石墨烯的碳化和结晶以及界面结构或缺陷对性能的影响方面。这在实际应用中是至关重要的，例如电子制造和性能。该研究项目还将培养3名博士生和3名硕士研究生，以及3名具有尖端知识和专业技能的PDF。这些学生和学员随后将在行业、学术和研究机构贡献他们的知识和技能，以增强加拿大未来在创新和创造力方面的竞争力。

This proposed research program will focus on direct laser writing process for rapid fabrication of copper-graphene (Cu-Gr) composite structures on various substrates for electronic applications by deeply understanding the correlations between laser processing conditions and interfacial structure of copper nanograins and/or copper-to-graphene junctions as well as electrical / thermal properties of composite structures and ultimately the performance of prototype flexible electronics. Three objectives of this research are to: (i) develop a one-step direct writing process for rapid patterning of Cu-Gr composite on various substrates; (ii) investigate the laser-induced heat generation, Cu nanoparticle formation and joining, polymer fast pyrolysis and Gr structure growing processes, particularly linking the laser heat generation to microstructures and defects at the interface of Cu-to-Cu and Cu-to-Gr to their conductivities; and (iii) design and fabricate prototype flexible electronics by utilizing different electrical and thermal properties of as-written Cu and / or Cu-Gr composite structures, and study their functions and performance related to microstructures and environmental stimuli. This research will use copper ion (e.g., Cu2+ and Cu+) and water soluble polymer (e.g., polyvinyl pyrrolidone-PVP, polyethylene glycol-PEG, and tannin) ink to coat the surface of substrates (plastics, silicon, paper) after proper surface treatment. Laser writing parameters will include laser power, scanning speed, wavelength, etc. Advanced analytical techniques will be used to investigate the formation of Cu and Gr and the defects at the interfaces of Cu grains or Cu-to-Gr. Electrical / thermal conductivities and mechanical property of as-written structures will be characterized. Simulations will be used to understand the growth of Gr on Cu surface under laser irradiation in a short time period. The as-written pure Cu and Cu-Gr composite structures will be integrated into functional devices on flexible substrates such as gas / strain sensor and photodetector to test their performances. The successful execution of this research program will provide a fundamental understanding of scientific phenomena in laser-mater interactions and microstructure-property correlation in materials science, specifically in laser heat generation, melting and solidification of metallic copper, atomic diffusion during joining, carbonization and crystallization of laser converted graphene, and effects of interfacial structures or defects on properties. This is of vital importance in practical applications, such as electronic fabrication and performance. This research program will also train 3 PhD and 3 MASc students and 3 PDFs with cutting edge knowledge and professional skills. These students and trainees will then contribute their knowledge and skills in industries, academic and research institutions to enhance Canada's future competitiveness in innovation and creativity.