Enhanced photoelectrochemical performance of carbon nanotubes-modified black TiO2 nanotube arrays for self-driven photodetectors

Self-driven ultraviolet photodetectors based on wide-bandgap semiconductors have been well investigated but are still being explored for further performance enhancement. Here we report a self-driven electrochemical ultraviolet photodetector (EUVPD) using a three-dimensional nanostructured photoanode based on defect-engineered TiO2 nanotube arrays (TNAs) modified with single-walled carbon nanotubes (SWCNTs) to enhance photoelectric performance. The EUVPDs based on Ar-annealed TNAs modified with 0.1 mg/mL of SWCNTs were found to have higher responsivity (∼60 mA/W), higher on/off current ratio (∼4.3 × 103), the faster response time (4 ms of rise-time and 27 ms of decay-time) when compared with unmodified and air-annealed ones. This performance enhancement is attributed to the highly efficient separation and transport of photoexcited carriers through the electrochemical redox reaction in the SWCNTs network anchored on the defect-engineered TNAs/electrolyte heterojunction nanostructure.