Low temperature synthesis of high quality 2D materials directly on flexible substrates remains a fundamental limitation towards realization of robust, strainable electronics possessing the unique physical properties of atomically thin structures. Here, we describe room temperature synthesis of uniform, stoichiometric amorphous MoS2, WSe2, and other transition metal dichalcogenides and subsequent large area (>5 cm2) photonic crystallization to enable direct fabrication of devices based on two-dimensional materials on large area flexible or rigid substrates. Fundamentals of crystallization kinetics for different monolithic and heterostructured TMDs are examined to apply this new synthesis approach for affordable, wearable devices. Example devices include photodetectors with photocurrent output and response times comparable to those fabricated via CVD and exfoliated materials on rigid substrates and the performance is unaffected by strains exceeding 5%. Flexible molecular sensors fabricated in this way detect diverse vapor phase substances with sub-ppm sensitivity. Functionalization of laser-written 2D TMD sensor transducers is also demonstrated for healthcare applications. Devices and circuits directly written from photonically annealed monolithic TMDs thin films deposited on large area flexible substrates, with no photolithography or patterning, are also presented. Additionally, other advanced processing strategies that enable flexible 2D materials will be discussed, including h-BN van der Waals liftoff of GaN HEMT devices for future strainable RF devices.
Dr. Nick Glavin is a materials scientist at the Air Force Research Laboratory in the Materials and Manufacturing Directorate and is a member of the flexible electronic research team within the Soft Matter Materials branch. He received his B.S. and M.S. in Chemical Engineering from the University of Dayton in 2010 and 2012, respectively, and his PhD in Mechanical Engineering from Purdue University in 2016. Upon completion of his PhD, he joined the Air Force Research laboratory, where his current research is specifically focused on flexible 2D materials, 2D/3D membranes, and laser processing of soft materials.
Dr. Christopher Muratore is the Ohio Research Scholars Endowed Chair Professor in the Chemical and Materials Engineering Department at the University of Dayton. Prior to joining the University, Professor Muratore spent 10 years as a staff member at the Air Force Research Laboratory and still works closely with multiple flexible electronics groups there. In 2013, he also founded m-nanotech Ltd., a consulting company specializing in thin film materials processing and characterization. Throughout his 20 year research career, Christopher’s work has focused on developing an understanding of how to control structure and properties of thin films and surfaces for diverse applications, and their impact on properties and performance. His research group currently focuses on novel large-scale synthesis of materials for flexible, wearable electronic devices. He has 4 patents, published over 80 peer-reviewed articles and has served as guest editor for Surface and Coatings Technology and Thin Solid Films for five years.