Interfacial Liquid Film Transfer Printing of Versatile Flexible Electronic Devices with High Yield Ratio

Abstract

Emerging flexible electronic devices differ widely in terms of material, shape, scale, and structure. The conventional solid‐contact stamp transfer printing method easily causes cracks and interfacial delamination in large‐area, intricately‐patterned multilayered devices. Liquid film transfer printing (LTP) is presented as a strategy to obtain flexible devices with a high yield ratio regardless of the device material, scale, shape, and structure. In this technique, the liquid film is used to hydrolyze and break the chemical bonds between the film and silicon wafer substrate. Thus, there is less stress on the device during the transfer process. In addition, the buoyancy and surface tension of the liquid film help the flexible device to unroll itself on the liquid surface. In the experiments, flexible devices of different types and with extreme properties consistently achieved a transfer printing yield ratio of 98.57%. The sensitivity of temperature sensor change before and after LTP is less than 2%. The real‐time and visualized comparisons of the stress distribution and evolution during LTP and solid‐contact methods demonstrated that the LTP maximum strain is 70% smaller than the latter method. Thus, LTP has great potential for sophisticated and system‐level flexible device transfer printing and integration.

Substrate‐Free Transfer of Large‐Area Ultra‐Thin Electronics

“…[ 19,22 ] Additionally, the liquid film transfer printing (LTP) is a technique that enables the fabrication of electronics without any damage and can be used with receiver substrates of different materials, patterns, and sizes. [ 23 ] Here, the electronics is fabricated on top of a silicon wafer containing a layer of PMMA. Then, an inorganic developer solution is used to hydrolyze the bonds between the PMMA and the silicon wafer, causing the PMMA layer to ascend and float on the liquid surface.…”

“…This allows for a large‐scale transfer of the electronics, enabling the adhesion on top of complex 3D arbitrary surfaces without any intermediate substrate layers, proving the suitability of the process for the utilization of novel and unconventional substrates. Differently from the LTP technique, [ 23 ] there is no intermediate layer between the devices and the substrates. The devices remained functional even with the presence of wrinkles.…”

“…[25] It enables the realization of multilayered metal-based devices by assembling the layers on top of each other without any substrate to hinder the contact between them. [18,23] Moreover, this technique also represents an environmentally-friendly approach to the fabrication of flexible electronics because some polymer layers can be dissolved and reused, such as PMMA, [26][27][28] reducing electronic waste during the fabrication steps and the disposal of devices. [29,30] Nevertheless, some limitations should also be considered.…”

Wafer-Recyclable, Eco-Friendly, and Multiscale Dry Transfer Printing by Transferable Photoresist for Flexible Epidermal Electronics

“…The mechanical property incompatibility between the metal and the flexible substrate may lead to interface destabilization during transfer printing. In addition, sacrificial layer-assisted processes often involve time-consuming wet chemical etching, which can potentially dissolve the flexible polymer substrates and disrupt the metal-substrate interface. ,, Furthermore, due to prolonged chemical etching with the diffusion of chemical etchants, delicate designs or large areas of transfer printing are limited.…”

Liquid Droplet Stamp Transfer Printing

“…Researchers use solution to dissolve the sacrificial layer, [55,56] take advantage of ferric chloride solution [57] and make use of bubbles produced by the redox reaction [58] to pick up the device from the substrate. For multilayer devices, Feng group use the liquid solution [59] and liquid drops [60] to transfer print small area multilayer devices. Rogers' group use PDMS stamps in stacking layers of functional materials and transferred multilayer devices.…”