Self-Powered UV Photodetector of TiO₂ with BaTiO₃ Surface Modification and Light-Controlled Logic Circuits...

One-dimensional (1D) metal oxides with excellent carrier transport and light absorption properties can be applied to photodetectors (PDs), facilitating device miniaturization, portability, and integration. Surface modification of 1D semiconductors can reduce carrier recombination in PDs as a way to increase photocurrent and decrease dark current of PDs. Herein, ultrathin BaTiO₃ (BTO) shell layers are grown on the surface of TiO₂ nanorod arrays (NRs) by in situ conversion using hydrothermal reaction, and the self-powered TiO₂-BTO NRs PDs are constructed. The effect of the thickness of BTO shell layers on the photoresponse characteristics of self-powered TiO₂-BTO NRs PDs is investigated by controlling the Ba²⁺ conversion concentration. The results show that the BTO shell layer reduces the dark current of the PDs because of the decreased interfacial transfer resistance and improved transfer of photogenerated carriers for building a "bridge" of carrier transport between BTO and TiO₂ due to the formation of Ti-O-Ti bonds. Moreover, the presence of the spontaneous polarization electric field in BTO enhances the photocurrent and response speed of PDs. The self-powered TiO₂-BTO NRs PDs are integrated in series and parallel to realize the functions of "and" and "or" gates of light-controlled logic gates. The ability to convert light signals into electrical signals for the self-powered PDs in real time demonstrates its great potential for optoelectronic interconnection circuits, which has important application prospects in the field of optical communication.