Formation of Triboelectric Series via Atomic-Level Surface Functionalization for Triboelectric Energy Harvesting

Abstract

Triboelectric charging involves frictional contact of two different materials, and their contact electrification usually relies on polarity difference in the triboelectric series. This limits the choices of materials for triboelectric contact pairs, hindering research and development of energy harvest devices utilizing triboelectric effect. A progressive approach to resolve this issue involves modification of chemical structures of materials for effectively engineering their triboelectric properties. Here, we describe a facile method to change triboelectric property of a polymeric surface via atomic-level chemical functionalizations using a series of halogens and amines, which allows a wide spectrum of triboelectric series over single material. Using this method, tunable triboelectric output power density is demonstrated in triboelectric generators. Furthermore, molecular-scale calculation using density functional theory unveils that electrons transferred through electrification are occupying the PET group rather than the surface functional group. The work introduced here would open the ability to tune triboelectric property of materials by chemical modification of surface and facilitate the development of energy harvesting devices and sensors exploiting triboelectric effect.

Mimicking Human and Biological Skins for Multifunctional Skin Electronics

“…For a structural approach, uniquely designed micro/nanoscale structures such as surface micropatterns, micropore, nanoscale assembly, and hierarchical nanoporous and interlocked microridge structures have been suggested, which enables the increases in surface area and stress‐induced deformability, thereby producing enhanced power up to a few tens of milliwatts. In addition, chemically modified surface charge by self‐assembled monolayers using an end‐fluorine terminated group, thiol with a different head group, and atomic‐level halogens and amines influences the surface potential and surface charge density, enabling control of triboelectric output.…”

Modulation of surface physics and chemistry in triboelectric energy harvesting technologies

“…The output power of the corresponding TEG was enhanced by almost 4 times. A wide spectrum of controllable triboelectric polarity was obtained through the functionalization of surfaces with the halogen (Br, F and Cl)-containing molecules or the aminated molecules, as shown in Figure 6(b) [104]. Here, hydroxyl surface groups formed by oxygen plasma treatment played a crucial role as strong covalent bonds between the substrate and the molecules.…”

“…(b) Schematic illustrations of surfacefunctionalized polyethylene terephthalate (PET) substrates with various organic molecule head groups for negatively or positively charging. Reprinted with permission from[104]. Copyright 2017 American Chemical Society.…”

Controlling Surface Charge Generated by Contact Electrification: Strategies and Applications

“…e) Results from contact electrification of poly(ethylene terephthalate) (PET) functionalized with different types of functional groups on its surface and unmodified PET. d,e) Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…Coating surfaces is another way to control the amount of charge generated by contact electrification. For example, coating self‐assembled monolayers (SAMs) of nonionic molecules of different types of functional groups on surfaces has been demonstrated to give rise to a wide range of charging behavior . In one experiment, the surface of poly(ethylene terephthalate) (PET) was coated with SAMs of nonionic molecules that consisted of halogen‐terminated arylsilane molecules and aminated molecules (Figure d).…”