Enhanced output performance and stability of triboelectric nanogenerators by employing silane-based self-assembled monolayers
The triboelectric nanogenerator (TENG) that can harvest environmental mechanical energy has been considered as a promising solution in driving wearable electronics. In order to maximize the surface charge density, intense efforts have been devoted to the development of various geometrical micro-/nanostructures on triboelectric surface. However, this approach is generally low throughput and high cost, making it highly challenging for practical applications. In this study, we present a promising strategy to simultaneously enhance the performance and stability of TENGs by using silane-based self-assembled monolayers (SAMs). The silane-based SAM molecules, including fluorinated molecules with different numbers of fluorine (F) atoms and 3-aminopropyl triethoxysilane (APTES), are employed as the surface modification layer for polydimethylsiloxane (PDMS) dielectric layer and aluminum (Al) electrode, respectively. The trichlorosilane groups on these SAMs can hydrolyze to form covalent bond to the substrate, enabling TENG to afford admirable device characteristics. Among the fluorinated molecules investigated herein, SAM based on 1H,1H,2H,2H-perfluorododecyltrichlorosilane (F21) affords the highest output characteristics due to the most distinct difference in the ability to attract surface electrons from Al layer to PDMS, delivering open circuit voltage (Voc) of 600 V and short circuit current (Isc) of 52 μA. The device performance can be further improved by incorporating APTES SAM on Al surface, and Voc of 873 V and Isc of 78 μA are attained. To the best of our knowledge, these characteristics represent the highest output performance ever reported for SAM-modified TENG. Importantly, the resulting TENG also exhibits good durability, maintaining 96 % of its initial voltage output after 250,000 cycles of repeated test. More encouragingly, our strategy is also applicable for large-area TENGs. The present findings indicate that tailoring the atomic-scale interfacial properties plays an important role in the development of high-performance and stable TENG.