Electro-chemo-mechanics theory in transfer printing of thin films in electrolyte solutions

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Transfer printing of thin films on an electrode substrate such as graphene on as-grown metal substrates in an electrolyte solution environment by applying an electrical field has provided a facile manufacturing technique to attain a precise delivery and assembly of thin film-based structures in a broad range of materials. The technique is underpinned by the electro-chemo-mechanical interfacial delamination, yet the fundamental theory is lacking. In the present study, we have established a comprehensive electro-chemo-mechanics theoretical framework of film detachment from various electrode substrates in an electrolyte solution environment. The bubble nucleation and subsequent kinetic growth due to the electrolysis of solution are first proposed and incorporated into the crack propagation of interface to predict the delamination of film from inert metal electrode substrates. Then, the film detachment induced by electrochemical etching to both interfacial bonds of film/electrode substrates and electrode substrates with chemically active metal materials is systematically investigated. The etching resultant kinetic model of bond breaking and failure is developed and also coupled with the bubble growth-induced interfacial delamination to describe their synergistic effect on the film detachment from electrode substrates with both types of electrode materials and polarity (i.e. anode or cathode). Afterward, we have implemented the electro-chemo-mechanics models into finite element method though a subroutine program. Computational results show remarkable agreement with theoretical predictions for both delamination mechanisms of solution electrolysis and electrochemical etching, regardless of materials of films, substrates and electrolyte solutions, and also are well confirmed with experimental results from literature in a good consistency. Further, a mechanical peeling force model equivalent has been developed to quantitatively estimate the electrochemical reaction-induced delamination and to discuss the application capacity of electrical field assistant transfer printing. The established electro-chemo-mechanics theory is expected to lay a foundation for quantitative understanding and controlling of transfer printing of thin films by the electrochemical field.