A hybrid ultrovilet detector based on polystyrene sulfate modified TiO2 nanocrystalline film

Abstract A hybrid polystyrene sulfate (PSS) modified TiO 2 nanocrystalline (NC) composite film based ultrovilet (UV) photodetector (PD) was proposed in this study. TiO 2 NC film with uniform size distribution was deposited on FTO glass by doctor blading P25 TiO 2 nanoparticles. Through layer-by-layer self-assembly, PSS/TiO 2 composite film was prepared and it exhibits a high responsivity of 602 AW −1 , a large photo-to-dark current ratio of 193200% and a low dark current of 7 nA at only 0.1 V bias. The obtained high responsivity is almost 1–2 orders of magnitude higher than that of mostly reported TiO 2 NC film based UV PDs. The reason is attributed to the injection of electrons from PSS into conduction band of TiO 2 and the separation improvement of photogenerated electrons and holes by the rutile/anatase junction in the TiO 2 NC film. Considering the high responsive performances and facile low-cost fabrication, the proposed PSS/TiO 2 composite film based UV PD shows a bright prospect in large-area UV detection application.