Enhancement of self-powered ultraviolet photodetection of PZT films via the collective effect induced by introducing SnO2 electron transport layer

Ferroelectric materials are considered promising for self-powered ultraviolet (UV) photodetector applications due to their photovoltaic effect. However, due to the relatively low photocurrent of pure ferroelectric thin-film materials, ferroelectric-based photodetectors exhibit poor performance. In this work, a PbZr_0.52Ti_0.48O₃ (PZT)/SnO₂ heterojunction photodetector was fabricated using a low-cost sol-gel method. In the heterojunction, the highly conductive SnO₂ serves as an electron transport layer (ETL). Compared to conventional devices grown on fluorine-doped tin oxide (FTO) substrates, our PZT/SnO₂ heterojunction exhibited larger PZT grain sizes, (100) oriented PZT growth, and significantly enhanced remnant polarization (Pr = 56 μC/cm²). This polarization effectively couples with the built-in electric field in the PZT/SnO₂ heterojunction. SnO₂, with its low-temperature preparation and high electron extraction capabilities, acts as an electron transport layer, facilitating charge selection and transport, reducing charge recombination, and promoting photogenerated carrier separation, resulting in superior photosensitive performance. The PZT/SnO₂ heterojunction-based device demonstrated higher responsivity [R = 0.24 A/W], a higher detectivity [D∗ = 2.01 × 10¹² Jones], and faster response speed (the rise time and fall time values of 16 ms and 37 ms, respectively.) at zero bias compared to PZT-based devices, outperforming most previously reported self-powered ferroelectric photodetectors. Our work highlights that the introduction of the SnO₂ electron transport layer can provide a collective effect, offering a reliable strategy for developing simple and efficient self-powered UV photodetectors.