Interfacial Drawing: Roll-to-Roll Coating of Semiconducting Polymer and Barrier Films onto Plastic Foils and Textiles

Abstract

This paper demonstrates that a thin polymeric film (10−80 nm) can be continuously drawn from the meniscus of a nonpolar polymer solution at an air−water−fluoropolymer interface using a roll-to-roll process: "interfacial drawing". With this process, it is possible to control the thickness of the film by manipulating the concentration of the solution, along with the drawing velocity of the receiving substrate. We demonstrate the formation of thin films >1 m in length and 1000 cm 2 in area, using our custom-designed apparatus. Interfacial drawing has three characteristics which compare favorably to other methods of forming and depositing polymeric thin films. First, the films are solidified prior to deposition, which means that they can be used to uniformly coat nonplanar, rough, or porous substrates. Second, these films can be stacked into multilayered architectures without risk of redissolving the layer beneath. Third, for some materials, the process yields films with superior mechanical compliance for applications such as wearable or flexible devices, compared to films produced by spin-coating. We demonstrate the utility of interfacial drawing by forming thin films of various semiconducting polymers, including the active layers of all-polymer bulk heterojunction solar cells as well as barrier coatings. As part of these demonstrations, we show how floating polymeric films can be transferred easily to diverse substrates, including those with rough and irregular surfaces, such as textiles and fabrics.

Estimating the Density of Thin Polymeric Films Using Magnetic Levitation

“…, metal, oxide, or perovskite films). This approach will be useful for polymer chemists and materials scientists aiming to characterize and optimize properties of thin films formed using a variety of processes and would help address questions in polymer science, such as the effect of interfacial confinement on the nanoscale packing of polymer chains and the macroscopic properties of thin films.…”

“…Moreover, this technique can be directly applied to measure the density of polar polymer films, using a hydrophobic sacrificial layer and paramagnetic solution, as well as nonpolymeric films (e.g., metal, oxide, or perovskite films). This approach will be useful for polymer chemists and materials scientists aiming to characterize and optimize properties of thin films formed using a variety of processes 57 and would help address questions in polymer science, such as the effect of interfacial confinement on the nanoscale packing of polymer chains and the macroscopic properties of thin films.…”

Dewetting Dynamics of Sheared Thin Polymer Films: An Experimental Study

“…They also have been thoroughly examined both from a theoretical and experimental point of view. [8][9][10][11][12] The effects of viscoelasticity, 13 slip 14 or residual stresses 15 have been considered, as such films find many industrial applications in conformal, protective, optical or functional coatings [16][17][18][19] and electrical films. 20 A case less studied is the stability of multilayer structures, i.e.…”

Solid-Phase Deposition: Conformal Coverage of Micron-Scale Relief Structures with Stretchable Semiconducting Polymers

“…This process is not without its limits, as it appears to be incompatible with exceptionally brittle polymers and is unlikely to be applicable to substrates with reentrant surfaces (i.e., those with undercuts). It has also not been demonstrated over large areas, though solution spreading has been shown to be compatible with roll-to-roll processing, 33 and so, the compatibility of SPD with textured, flexible substrates seems likely. Regardless, because of its simplicity, expediency, and flexibility, we believe SPD could impact a wide range of fields, such as sensing, medicine, and energy.…”