Sustainable Sacrificial Layer Free Transfer of Thin-Film Electronics using a Super-Hydrophilic Substrate

Substrates commonly used in sustainable electronics fabrication are often too fragile to withstand traditional fabrication processes involving high temperatures, harsh chemicals, or vacuum conditions. Consequently, transfer methods such as stamping or water transfer printing, which often use sacrificial layers, are widely employed to move functional structures onto these delicate substrates. This paper presents a transfer process that entirely eliminates the need for sacrificial layers (e.g., poly(vinyl alcohol) (PVA) or poly(methyl methacrylate) (PMMA)) or time-consuming etching steps. We introduce a superhydrophilic (S-HP) substrate to enable the detachment of a variety of functional thin-film structures via careful optimization of the relative hydrophilicity levels. This delamination behavior results in freely floating functional structures on a water surface, which can be transferred onto arbitrary receiver substrates. The transfer process is successfully demonstrated with various substrates and a diverse range of metallic and semiconducting functional materials. Additionally, the method allows for the subsequent transfer and alignment of multiple thin-film structures to assemble electronic circuits on the secondary receiver substrate, as well as the use of elastomeric receiver substrates to create electronics stretchable in two dimensions. Furthermore, the S-HP donor substrate is fully reusable after all structures have been detached. This S-HP substrate water transfer method paves the way for next-generation sustainable electronics by enabling the integration of advanced functional structures onto substrates that cannot withstand traditional processing conditions.