High-performance self-driven photodetectors based on self-polarized Bi_0.9Eu_0.1FeO₃/Nb-doped SrTiO₃ p-n heterojunctions

Ferroelectric (FE) materials, owing to their remarkable photovoltaic effects, are one class of the most promising materials candidates for self-powered photodetectors. Here, with the pronounced rectification ratio as large as 10³ at electric bias of± 1.0 V and a low dark current of 12 pA, the self-polarized Bi_0.9Eu_0.1FeO₃ (BEFO)/Nb-doped SrTiO₃ (NSTO) p-n heterojunctions are synthesized. It is revealed that the BEFO/NSTO p-n heterojunctions achieve the excellent photovoltaic effect with a short-circuit current as high as 0.23 μA and an open-circuit voltage of 0.41 V under the light illumination of 405 nm in wavelength and intensity of 151.7 mW/cm². More importantly, the built-in potential in the as-prepared heterojunctions offers the self-powered photo-detecting functionality, with the high light-on/off current ratio of 2.0 × 10⁴, high responsivity of 0.64 mA/W and sensitive detectivity D* of 1.63 × 10¹⁰ Jones, and fast response speed of 50/44 ms without external bias voltage. In particular, the super-performance with R ~ 1.97 mA/W and D*~ 5.0 × 10¹⁰ Jones in the weak incident light intensity (1.4 mW/cm²) are demonstrated, better than most previously reported FE-based self-powered photodetectors. Moreover, the devices possess good ambient stability and reproducibility. This work provides a demo for optically driven high-performance electronic devices based on self-polarized ferroelectric materials.