Enhancing Triboelectric Nanogenerator Output by the Optimization of Amine Group Surface Functionalization

Abstract

<p>We studied the effect of surface functionalization with amine group-containing molecules on the electrical output performance of triboelectric nanogenerators (TENGs). The surface functionalization with an amine (–NH2) group featuring cysteamine, (3-aminopropyl)triethoxysilane (APTES), N-[3-(trimethoxysilyl)propyl]ethylenediamine (AHAPS), and N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMPTA) was performed to modify the surface. The formation of self-assembled monolayers (SAM) on the substrates was confirmed by contact angle measurements, x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). After surface functionalization with cysteamine molecules, the power output of the TENG was improved by about 3.3 times, ascribed to the boosted charge transfer from electron-donating amine groups compared with the pristine Au surface. Furthermore, the effect of the number of amine groups in the molecule on the electrical output was studied by modifying the polyethylene terephthalate/indium tin oxide (PET/ITO) surface with APTES, AHAPS, and TMPTA with one, two, and three amine groups, respectively. Relative to the pristine PET/ITO-based TENG, the induced charge density gradually increased by 4.5, 7, and 17 times as the number of amine groups increased in the functionalized samples. The peak power density of the TMPTA-based TENG was about 8.4 times higher than the APTES-based TENG, which is attributed to the presence of amine group-containing molecules that have stronger electron-donating strength on the surface, which enhances charge transfer at the interface between the triboelectrification layers.</p>