Fine-tuning grain size and porosity for enhanced performance of BiFeO3-based UV photodetectors

Ferroelectric BiFeO 3 , with a relatively low bandgap of 2.7 eV, is considered as an ideal candidate for self-powered ultraviolet (UV) photodetectors. However, due to its weak light absorption and low conductivity, BiFeO 3 -based photodetectors typically suffer from low photocurrent and inferior photosensing performance compared to other semiconductor photodetectors. In this study, BiFeO 3 -based photodetectors with varying grain sizes and porosity were prepared. A comprehensive analysis revealed that the photocurrent increased linearly with grain size and porosity. Larger grains improve electrical conductivity and charge transport, while increased porosity enhances light trapping and effective optical absorption. Consequently, the photodetector based on BiFeO 3 ceramics with average grain size of 12.8 μm exhibited a notable photocurrent density of 5.01 mA/cm 2 , corresponding to a high responsivity of 14.35 mA/W and a detectivity of 2.76 × 10 11 Jones under 365 nm illumination. These values represent enhancements of 2.4 and 6.5 times, respectively, compared to the device fabricated with smaller grains (∼0.78 μm). This work establishes the relationship between grain size, porosity, and the photosensing properties of BiFeO 3 ceramics, clarifying how these factors influence performance. It offers a promising approach for enhancing the performance of BiFeO 3 -based photodetectors and advancing their application in self-powered UV light detection.