Self-driven ultraviolet photodetectors based on ferroelectric depolarization field and interfacial potential

Self-powered ultraviolet photodetectors have attracted considerable interest for their reduced sizes and high portability which makes them possible for application in a hazardous environment. In this work, Pb0.95La0.05Zr0.54Ti0.46O3 (PLZT) thin films with a wide bandgap of similar to 3.72 eV and large remanent polar-ization of similar to 33.9 mu C/cm(2) were synthesized by low-cost sol-gel method, based on which, highly sensitive self-powered ultraviolet (UV) photodetectors with a Au/PLZT/FTO structure were developed. It's found that the responsivity of the devices can be modulated by changing the direction of polarization in the PLZT thin film owing to coupling effects of the depolarization electric field with interfacial barriers at both Au/PLZT and PLZT/FTO contacts. The devices with PLZT in downward polarization state show a remarkable responsivity of 0.011 mA/W at zero bias to illumination of 340 nm-light with fast-response rise time of 98 ms and decay time of 96 ms. The present work sheds light on the design of self-driven photodetectors free of the p-n junction on the basis of ferroelectric oxides. (C) 2020 Elsevier B.V. All rights reserved.