Self-Powered Deep-Ultraviolet Photodetector Driven by Combined Piezoelectric/Ferroelectric Effects

In this study, in situ piezoelectricity was incorporated into the photoactive region to prepare a self-powered deep-ultraviolet photodetector based on a mixture of polyvinylidene fluoride (PVDF)@Ga₂O₃ and polyethyleneimine (PEI)/carbon quantum dots (CQDs). A ferroelectric composite layer was prepared using β-Ga₂O₃ as a filler, and the β-phase of PVDF was used as the polymer matrix. The strong piezoelectricity of β-PVDF can facilitate the separation and transport of photogenerated carriers in the depletion region and significantly reduce the dark current when the device is biased with an external bias, resulting in a high on/off ratio and high detection capability. The self-powered PD exhibited specific detectivity (D* = 3.5 × 10¹⁰ Jones), an on/off ratio of 2.7, and a response speed of 0.11/0.33 s. Furthermore, the prepared PD exhibits excellent photoresponse stability under continuous UV light, with the photocurrent retaining 83% of its initial value after about 500 s of irradiation. Our findings suggest a new approach for developing cost-effective UV PDs for optoelectronic applications in related fields.