A Tunable Polarization Field for Enhanced Performance of Flexible BaTiO 3 @TiO 2 Nanofiber Photodetector by Suppressing Dark Current to pA Level

The flexible titanium dioxide (TiO 2 ) nanofibers (NFs) film are promising candidates for high‐performance wearable optoelectronic devices. However, the TiO 2 ultraviolet photodetectors (UV PDs) generally suffer from low photosensitivity, which limits the practical applications. Herein, a TiO 2 (TO) NFs film flexible photodetector integrated by ferroelectric BaTiO 3 (BTO) NFs is developed via electrospinning technology with double sprinklers and in situ heat treatment. Compared with TO NFs PD with poor on/off ratio ≈44, the BTO@TO NFs PD‐2 exhibits an excellent on/off ratio of ≈1.5 × 10 4 due to the dramatically restrained dark current. The ultralow dark current (pA level) is attributed to the depletion of photogenerated carriers by the space high‐resistance state induced by the downward self‐polarization field in ferroelectric BaTiO 3 NFs. The ferroelectric domain with larger downward orientation in polarized BTO@TO NFs exhibits stronger self‐polarization field to modify the directional transport of photogenerated carriers and enhances the band bending level, which improves the photocurrent of device. The special structure woven by ferroelectric nanofiber with self‐polarization will provide a promising approach for improving the performance of flexible photodetectors.