Controlled fabrication of nanoscale wrinkle structure by fluorocarbon plasma for highly transparent triboelectric nanogenerator

Abstract

In this paper, we report a novel nanoscale wrinkle-structure fabrication process using fluorocarbon plasma on poly (dimethylsiloxane) (PDMS) and Solaris membranes. Wrinkles with wavelengths of hundreds of nanometers were obtained on these two materials, showing that the fabrication process was universally applicable. By varying the plasma-treating time, the wavelength of the wrinkle structure could be controlled. Highly transparent membranes with wrinkle patterns were obtained when the plasmatreating time was o 125 s. The transmittances of these membranes were 490% in the visible region, making it difficult to distinguish them from a flat membrane. The deposited fluorocarbon polymer also dramatically reduced the surface energy, which allowed us to replicate the wrinkle pattern with high precision onto other membranes without any surfactant coating. The combined advantages of high electron affinity and high transparency enabled the fabricated membrane to improve the performance of a triboelectric nanogenerator. This nanoscale, single-step, and universal wrinkle-pattern fabrication process, with the functionality of high transparency and ultra-low surface energy, shows an attractive potential for future applications in microand nanodevices, especially in transparent energy harvesters. INTRODUCTIONPatterned surface structures on the nano-or micrometer scale have a significant role in the properties of a material, including physical, mechanical, electrical, and optical 1 . The fabrication process for these patterns has been traditionally realized by photolithography, printing processes, embossing, or writing techniques, of which the relatively high cost and low throughput limit their application for producing complex topologies over large areas. Thereby, selfassembled patterns for large-area patterning, which generally employ physical-chemical or mechanical instabilities within a constrained system to form highly ordered structures, have attracted great attention for many years 2-7 . Among these methods, mechanically inducing a wrinkle structure on a bilayer system is especially suited to creating highly ordered microstructures across a large surface and features convenient fabrication and a tunable wavelength by adjusting the thickness of the stiff layer and the prestrain [8][9][10][11][12] . As a result, wrinkle structures have been used in various applications, such as smart adhesion, liquid/cell shaping, particle assembly, optical surfaces, flexible electronic devices, and energy harvesters [13][14][15][16][17][18][19][20] . To date, most studies involving wrinkling to create ordered structures rely on plasma or ultraviolet-ozonolysis (UVO) oxidation and metal deposition to create the stiff skin. Although these approaches are quite practical, the material properties of the substrate during oxidation can significantly alter the typical morphologies and even block the formation of the wrinkle structure (that is, the process does not have universality to different materials), whereas the deposition of the metal la...

Effect of Low-Pressure Plasma Treatment Parameters on Wrinkle Features

“…The activated ion particles in the plasma collide with a rigid surface and exert stress in all directions of the surface. Plasma treatment creates wrinkle structures with random directionalities that can enhance the mechanical and optical properties in all directions [ 12 , 13 , 14 , 15 ].…”

Emergent Soft Lithographic Tools for the Fabrication of Functional Polymeric Microstructures

“…These techniques support a diverse range of applications, including, but not limited to: microelectronics, [91,130,144] superhydrophobic surfaces, [73,89,90,[104][105][106] micro-lenses, [93,95] open channel microfluidics, [92] structural color, [104,105,115,124,125] cellular growth environments, [137,145,146,153] and triboelectronics. [82][83][84]128] We anticipate that this list will continue to grow as more scientists adopt the strategies represented by these new fabrication techniques. Self-forming masters enable PMs with hierarchical microstructures while simultaneously alleviating the need for photolithography in master fabrication; liquid-based soft lithographic techniques enable the fabrication of PMs with molecularly smooth surfaces of increasingly complicated geometries with convex/concave features determined by readily tunable liquidsubstrate interactions; 3D soft lithography with natural materials and sacrificial masters enables the fabrication of PMs with interpenetrating and hierarchical morphologies; dynamic masters enable the fabrication of large numbers of geometrically distinct PMs from a limited set of templates, highlighting the important role active supports can play in materials fabrication; screen-based masters enable the fabrication of heterogeneous PMs that are based on the patterned sorting of microparticle building blocks.…”

“…[73] Wrinkled surfaces, in addition to being PMs themselves, can be used to fabricate PMs of other materials by aligning polymer microparticles in the troughs of the wrinkles, [74][75][76] by using the relief microstructure of the wrinkles as stamps for μCP, [77][78][79] or by reproducing the wrinkles with replica molding and embossing procedures. [80,81] Wrinkled microstructures can be applied to the fabrication of PMs for many technological applications, including: triboelectric nanogenerators, [82][83][84] wettability patterns, [80,85] optically active surfaces, [81,86] smart adhesives with contact splitting properties, [87] and anti-fouling surfaces. [88] Surfaces with hierarchical wrinkles can be used as masters for replica molding in order to fabricate PMs with hierarchically wrinkled surfaces ( Figure 2D).…”

Review of fundamentals and applications of polyester nanocomposites filled with carbonaceous nanofillers

“…77 These devices may be optimized to attain high efficiency, low power consumption, recharge-ability, and energy storage. [68][69][70][71][72][73][74][75][76][77][78][79][80] Huang et al 81 fabricated a polyesterbased flexible supercapacitor coated with carbon nanotubes. The supercapacitor showed fine specific capacitance equal to 15.67 cmF/cm 2 with 90% stability after 1000 cycles.…”