Ice-glue assisted transfer printing of nanocarbon black and its application for electroplating ultrafine copper wires†

Abstract

PDMS-assisted transfer printing has been widely applied in the patterning and device integration process of optoelectronic thin films. However, a traditional transfer method is not suitable for nanomaterials. This is due to the generally low adhesion between nanomaterials and rigid substrates because of the incomplete contact between them caused by the irregular geometric shape of nanomaterials, which is crucial for successful transfer. Here, we introduce a simple and low-cost technique named “ice glue-assisted transfer printing” as a solution to overcome the limitations of the previous method. Benefiting from the ease of reaching the triple point temperature of water, controllable transfer printing of nanomaterials using PDMS stamps can be achieved by utilizing the differences in the mechanical properties of water in different phase states. The transfer characteristics of PDMS stamps to different nanomaterials were investigated, especially in terms of transfer amount and pattern accuracy. The results indicate that, for hydrophobic nanomaterials such as nanocarbon black (NCB), ice-assisted transfer printing can transfer the majority of nanomaterials to the target substrate from the PDMS stamp, whereas, for hydrophilic nanomaterials such as silver nanowires, the complete transfer can be achieved. Most importantly, experimental results also show that water amount and post-processing temperature have a significant impact on the accuracy of transfer printing patterns. Based on this, condensation pretreatment was proposed to introduce an ultra-thin ice layer on the target substrate surface, thereby achieving high-precision patterned transfer printing. Finally, shrinkage transfer printing was proposed to improve the pattern accuracy via prestretching the PDMS stamp, which was successfully applied to the preparation of ultrafine metal wires based on the nanoconductive carbon templated area-selective electroplating method.