Publication

Abstract : The synthesis of silver bismuth iodide (SBI) nanocomposite thin films for visible light photodetection application is reported. The formation of different compositions of SBI (AgBiI4 or Ag2BiI5) is achieved by varying the Ag precursor concentration in the solution. Heat treatment of the films at 125 °C for 15 min results in crystalline AgBiI4 and Ag2BiI5 pin-hole free films and displays uniform coverage of the surface with densely packed grains. The grain sizes in the films are >100 nm for AgBiI4 and >300 nm for Ag2BiI5. The direct optical band gaps are 1.63 and 1.66 eV for the AgBiI4 and Ag2BiI5 films, respectively, making them suitable for light-harvesting applications. The fabricated films exhibit good photodetector responsivity and detectivity under 454 nm light illumination. At 1 V bias, the photoresponsivity of Ag2BiI5 films was 1.25 × 105 A/W with specific detectivity of 3.8 × 107 Jones. A photocurrent on/off ratio of approximately 39.6, a photoresponse rise time of 1.99 s, and a fall time of 2.04 s were also observed. The Ag2BiI5 perovskite films show better performance for photodetector applications than AgBiI4 films.