Transfer printing is a technique of assembling layered structures in which a thin film or layers of thin films processed on a source substrate are picked and released onto a target substrate. This operation is performed successively until the desired layered structure is formed. This process is widely used in the fabrication of micro- to nano-scale thin film based devices, especially in the production of flexible electronics. In current practice, the technique relies heavily on trial and error, which results in low yields. This is particularly true for the transfer of thin films with multiple layers or discrete structures, where damage and residual contamination are quite common. This award will focus on the fundamental study of detachment mechanics of thin film-substrate systems in a liquid environment. The outcome of this research will impact the design and execution of transfer printing process through development of simple steps and relationships for high, yet efficient, throughput. This research is an interdisciplinary study involving chemo-mechanics, materials science and manufacturing. Graduate and undergraduate students will be exposed to and trained on a broad scope of education and skills, respectively. Undergraduate students form underrepresented groups will be actively recruited and a university program will be leveraged to perform K-12 outreach.
Transfer printing is emerging as a competitive technique in the delivery and assembly of thin films in manufacturing. Its working efficiency is inherently underpinned by the detachment mechanics of thin films from substrates. The liquid-assisted transfer printing technique could promote both yield and quality of the detachment of thin films and involves a synergistic interplay of external mechanical loading and chemical reactions at the solid-liquid interface. The project will conduct a comprehensive study of liquid-assisted interfacial detachment in film-substrate systems, where the presence of liquid water will react with interfacial materials, leading to a controllable and selective detachment of thin film layers. The outcome of this study will be two-fold: 1) a comprehensive chemomechanics theory of liquid-driven detachment mechanics, and 2) a hybrid computational modeling framework that bridges solid-liquid atomistic interactions (mechanism) and continuum phenomena of film detachment (structural function) with validation from experimental testing and theory. The research will impact the transfer printing fabrication technique by providing scientific and technological means to achieving efficient, quantitative throughput.
