Intuitive Polydimethylsiloxane Deposition Relying on Resource Conservative, Large Scale Compatible Capillary Flow Dynamics.

With the increased demand for flexible and wearable electronics, the need for alternative and accessible large-scale compatible production methods for polymer thin films has never been more urgent. Polydimethylsiloxane (PDMS) has shown immense promise in various applications because of its versatile chemical and physical properties, though a waste free, industry scale, and highly controllable production technique has yet to be introduced. Herein, we propose an intuitive approach to PDMS film fabrication relying on capillary action to grow a ready-to-use large-scale layer from a relatively small volume of solution-processed precursor with zero waste. The technique, referred to as capillary crawl film formation, or CCFF, introduced in this work is simple, primarily focused on limiting consumable resources and manual processing steps and on enabling large monolithic structures. We demonstrate precise control over the dimensions and morphology of the cured PDMS films without discarding any residual unwanted material; thicknesses ranging from μm to mm, both small- and large-scale surfaces, and varying degrees of preliminary 2D and 3D microstructuring are effortlessly added to all polymer surfaces during concurrent layer formation, for an even wider range of applications. The different film properties formed by either horizontal or vertical CCFF are tuned by modifying the solution volume, the dimension, adhesion, and morphology of the substrates used. Finally, we use CCFF to demonstrate its applicability for sensory applications, healing torn polymer films, and as an excellent encapsulant for perovskite solar cells where no drop in their 21% efficiency achieved was recorded in over a 1300 h testing period under ambient and high humidity conditions, promoting great device stability and longevity.