Ferroelectric Polarization‐Enhanced Performance of Flexible CuInP₂S₆ Piezoelectric Nanogenerator for Biomechanical Energy Harvesting and Voice Recognition Applications

Abstract

2D piezoelectric materials have strong intrinsic piezoelectricity and superior flexibility, which are endowed with huge potential to develop piezoelectric nanogenerators (PENGs). However, there are few attempts to investigate the energy harvesting of 2D ferroelectric materials. Herein, an enhanced output performance is reported by ferroelectric polarization in a PENG with exfoliated 2D ferroelectric CuInP2S6 (CIPS). Specifically, the polarized CIPS‐based PENG produces a short‐circuit current of 760 pA at 0.85% tensile strain, which is 3.8 times higher than that of unpolarized CIPS‐based PENG. Systematical PFM and Raman analysis reveal that the ferroelectric polarization remarkably reinforces the effective piezoelectric constant of CIPS nanoflakes and boosts the in‐plane migration and out‐of‐plane hopping of copper ions, which is the main reason for the enhancement of output performance. Furthermore, the CIPS‐based PENG can not only be utilized to harvest biomechanical energy such as wrist joints movement, but also exhibits a potential for a voice recognition system integrated with deep learning technology. The classification accuracy of a series of letter sounds is as high as 96%. This study commendably broadens the application scope of 2D materials in micro‐nano energy and intelligent sensors, which will have profound implications for exploring wearable nanoelectronic devices.

Ferroelectricity-Driven Self-Powered Weak Temperature and Broadband Light Detection in MoS2/CuInP2S6/WSe2 van der Waals Heterojunction Nanoarchitectonics

“…Insets illustrate the corresponding SAED patterns, indicating a high crystal quality of these materials utilized in this work. The interplanar spacings of the (100) planes were observed to be 0.29, 0.56, and 0.28 nm in MoS 2 , CuInP 2 S 6 , and WSe 2 , respectively, which are consistent with the previous work. ,, …”

“…In recent years, the emergence of two-dimensional (2D) ferroelectric materials has opened up exciting possibilities for self-powered van der Waals (vdW) detectors due to their atomically thin thickness, surface devoid of dangling bonds, diverse material options, and the ability to construct them without the need to consider lattice mismatch problems. − Owing to the pyroelectric and bulk photovoltaic effects, temperature and light detectors based on 2D ferroelectric materials have shown great potential in applications such as optical communications, optical imaging, and optical sensing, as well as remote sensing and biomedical imaging. − Their application in self-powered temperature and light detectors can reduce system volume and power consumption of the photodetection, which has a promising application prospect. − By incorporating both the pyroelectric and bulk photovoltaic effects driven by ferroelectricity, 2D ferroelectric materials offer enhanced modulation degrees of freedom in self-powered van der Waals temperature and light detectors . However, in addition to the low polarization, the practical applications of these materials are limited due to the significant challenge posed by their ultrathin nature, which affects their polarization stability .…”

“…The interplanar spacings of the (100) planes were observed to be 0.29, 0.56, and 0.28 nm in MoS 2 , CuInP 2 S 6 , and WSe 2 , respectively, which are consistent with the previous work. 11,28,29 Figure 2a presents an AFM image of the heterojunction, and the insets show that the thickness of MoS 2 , CIPS, and WSe 2 nanoflakes is approximately 56, 45, and 82 nm, respectively. The active area is about 667 μm 2 .…”

Improved Energy Harvesting Ability of Single-Layer Binary Fiber Nanocomposite Membrane for Multifunctional Wearable Hybrid Piezoelectric and Triboelectric Nanogenerator and Self-Powered Sensors

“…Preparation of Co-electrospinning Nanofiber Membrane. Initially, different concentrations (12,14,16,18, and 20 wt % for PVDF; 10, 12, 14, and 16 wt % for PAN) and voltages (8, 10, 14, and 18 kV) were explored to electrospin neat PVDF and PAN fiber membranes, respectively (Figures S20−S22, Supporting Information). Optimal spinning parameters, including a fixed temperature of 30 °C, solution flow rate of 1 mL h −1 , solution concentration (20 wt % for PVDF and 14 wt % for PAN), voltage of 14 kV, collection distance of 15 cm, and rotational speed of 400 rpm, were determined and maintained throughout the study.…”

“…Numerous materials and structures have been investigated to enhance the electrical output of PENGs. − Polyvinylidene fluoride (PVDF) and its copolymers, characterized by the presence of ferroelectric β-phase crystals, stand out as popular choices due to their outstanding piezoelectric properties . However, as electronic devices and integration technologies continue to evolve, conventional PVDF-based nanogenerators struggle to meet the escalating demands of energy consumption.…”