Dramatic Responsivity Enhancement Through Concentrated H 2 SO 4 Treatment on PEDOT:PSS/TiO 2 Heterojunction Fibrous Photodetectors

In order to satisfy the growing requirements of wearable electronic devices, 1D fiber‐shaped devices with outstanding sensitivity, flexibility, and stability are urgently needed. In this study, a novel inorganic‐organic heterojunction fibrous photodetector (FPD) based on poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and highly ordered TiO 2 nanotube array is fabricated, which endows a high responsivity, large external quantum efficiency, and fast response speed at 3 V bias. To further ameliorate its performance in the self‐powered mode, a facile acid treatment is adopted and the assembled H‐PEDOT:PSS/TiO 2 FPD demonstrates outstanding self‐powered properties with ≈3000% responsivity enhancement (161 mA W −1 at 0 V under 365 nm irradiation, photocurrent enhancement of ≈50 times) compared with the untreated device. It is found that the concentrated H 2 SO 4 post‐treatment helps decrease the tube wall thickness of TiO 2 and partially removes the insulated PSS component in PEDOT:PSS, leading to enhanced conductivity and facilitated charge transportation, and thereby superb responsivity/photocurrent enhancement of self‐powered H‐PEDOT:PSS/TiO 2 FPD. This low‐cost and high‐performance self‐powered FPD shows high potential for applications in wearable electronic devices.