# Piezo‐Phototronic PVDF/HfO2/Nano‐Cu Heterostructured Thin Film for Flexible Self‐Powered Multimodal Sensing

## TL;DR

A flexible, self-powered sensor made from PVDF, HfO2, and nano-Cu can detect both pressure and light, showing promise for wearable and aerospace technologies.

## Contribution

A novel heterostructured nanofiber membrane combining piezoelectric and piezo-phototronic effects for dual-mode sensing.

## Key findings

- The sensor achieves an output voltage of 15V and remains stable over 5000 cycles.
- The photodetector shows high photoresponsivity (5.67 mA/W) and rapid response times.
- The device exhibits a 28.6% current enhancement under simultaneous light and pressure.

## Abstract

The pursuit of multifunctional sensors has intensified due to their potential for integrated, efficient operation. However, realizing a flexible material that combines simplicity in the fabrication process with high performance and multifunctionality remains a formidable challenge. In this study, a multi‐interface heterostructured nanofiber membrane composed of Polyvinylidene fluoride (PVDF), HfO2, and nano‐copper is fabricated, leveraging the synergistic interplay of piezoelectric and piezo‐phototronic effects for flexible, self‐powered sensing. The incorporation of hafnium oxide (HfO2) and nano‐Cu enhances the crystallinity of the piezoelectric β‐phase and improves the dielectric properties, substantially boosting electromechanical performance. The resultant piezoelectric sensor achieves an output voltage of 15V and maintains stability over 5000 cycles at 5 Hz, enabling precise detection of human motions. Meanwhile, the PVDF/HfO2‐based photodetector exhibits broadband sensitivity (from near‐UV to near‐IR), high photoresponsivity (5.67 mA W−1), high detectivity (4.14×1011 Jones), and rapid response (600 µs rising, 53 µs falling). Critically, the device demonstrates a 28.6% current enhancement under simultaneous light and pressure, highlighting a strong piezo‐phototronic effect. This work presents a multifunctional fiber film for dual‐mode sensing (pressure & light), with promising applications in wearable electronics and aerospace systems. Its straightforward fabrication and high performance offer a viable pathway toward next‐generation, flexible, self‐powered sensors.

Electrospinning a composite of PVDF, HfO2, and nano‐Cu transforms the discrete precursors into a continuous nanofiber mesh, forming a multi‐interface heterostructure with embedded nanoparticles. The presence of HfO2 and nano‐Cu at the fiber interfaces induces a highly aligned β‐phase, which enhances piezoelectric crystallinity and improves the material's dielectric properties.