3D copper telluride morphological leaf structure based triboelectric nanogenerator for wearable sensing application

Abstract

Enhancing the performance of triboelectric nanogenerators (TENGs) requires significant advancements in the triboelectric charge density, which is closely related to the electron affinity differences between materials and their surface-contact modifications. Metal telluride materials, particularly copper telluride (Cu₂Te), are promising materials owing to their exceptional semiconducting properties and superionic conductivity. This study introduces a novel method using single-step chemical vapor deposition (CVD) to directly synthesize three-dimensional (3D) Cu₂Te leaf-like structures on Cu substrates. Incorporating 4 wt% Cu₂Te into a polyvinylidene fluoride (PVDF) matrix enhances the charge transfer properties by inducing β-phase crystallinity, aligning the molecular dipoles, and increasing the polarization. The highly electronegative nature of PVDF plays a crucial role in optimizing the triboelectric charge separation by significantly enhancing the electron affinity at the interface. At the same time, Cu₂Te further facilitates interfacial charge transfer through its high conductivity and large surface area. Complementing this, the PVA/NaCl tribopositive layer with a 0.2 M NaCl concentration leverages disrupted hydrogen bonding within the PVA matrix caused by ion–dipole interactions with Na⁺ ions. These interactions increase the availability of free hydroxyl groups, thus enhancing the electropositivity and charge generation. The PVDF/Cu₂Te and PVA/NaCl layers establish a strong triboelectric interface, thereby optimizing the charge transfer and retention. The TENG structure, with an area of 20 cm², achieved a peak open-circuit voltage of 170 V, a short-circuit current of 32 µA, and a power density of 1.62 W/m² at an impedance of 40 MΩ. The device demonstrated remarkable durability over 80,000 operational cycles and maintained stable performance after 30 days of testing. Additionally, the TENG successfully powered 56 LEDs, a stopwatch, and charged capacitors in the range of 1 μF, 10 μF, and 22 μF for self-powered electronics, demonstrating its potential for wearable sensing and sustainable electronic applications. This study highlights the potential of metal telluride materials to advance TENG technology for high-performance energy harvesting and self-powered electronic devices.