Self-Powered UV Photodetectors Based on Hydrothermal Barium Titanate Film Modified With Reduced Graphene Oxide Nanolayer

TiO2-based nanomaterials have been well-studied for building high-performance ultraviolet (UV) photodetectors (PDs). However, their low interface crystallinity has always limited the creation of photogenerated carriers. In this work, a highly efficient, self-powered reduced graphene oxide (rGO)/barium titanate (BaTiO3, BTO) UV PD with a flexible structure is presented. The hydrothermal BTO film, grown from a TiO2 structure with very good polarization and ferroelectric properties, rGO, possesses a large surface area and good carrier mobility. The self-polarized electric field of the BTO film regulates carrier separation with the assistance of the rGO nanolayer, thus increasing photogenerated carrier generation. The fine crystalline structure of BTO film with a crystal size of 16.2 nm is verified. A coercive field of 7 kV/cm for the rGO/BTO device is less than that of 12 kV/cm for the BTO device. Lower coercive fields tend to have faster switching times, stability, and energy efficiency. The response (I–t) of the PDs was done under an isolated chamber containing a UV source having an intensity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6~\mu $ </tex-math></inline-formula>W<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{2}}$ </tex-math></inline-formula>. The responsivity of BTO and BTO/rGO devices is found to be 0.185 and 29.4 A/W, respectively. The current-voltage (I–V) characteristic was affected by different poling schemes. The temperature effect of the UV PDs is also investigated for practical application. Results show that a significant photocurrent increase was obtained for the rGO device for different poling and temperature conditions under self-powered operation.