Synthesis and characterization of thin films of P3HT − G/MoS2 nanocomposites in photodetectors applications

Abstract. The nanocomposite, poly(3-hexylthiophene-2,5-diyl) (P3HT)–graphene/molybdenum disulfide (MoS2), was for the first time fabricated by the pulse laser ablation (PLA) method with different numbers of laser pulses deposited onto a porous silicon (PSi) substrate using the drop-casting technique. Nanocrystalline PSi films are prepared by electrochemical etching of a P-type silicon wafer. The optical properties, transmission electron microscope (TEM), and photodetector properties were studied. Optical measurements confirmed that the energy gap decreases from 2.03 to 1.87 eV with the increasing number of laser pulses for graphene and MoS2. This decrease in the energy gap was attributed to the increase in graphene and its combination with molybdenum. Due to the higher electrical conductivity of the hybrid material, the MoS2 leads to reduce the band gap. From the TEM images, it was found that the average size of the particles was between 3.1 and 20.8 nm depending on increasing the number of laser pulses for both graphene and MoS2 with hemispherical particle shapes. The Ag  /  PSi  /  P3HT  −  G  /  MoS2  /  Ag photodetector was fabricated for all samples prepared to characterize the effect of laser pulses number for graphene and MoS2 on the photodetector performance. The maximum value of the specific response, specific detection, and quantum efficiency was 0.35  A  /  W, 5.1  ×  1012  cm Hz1/2 W  −  1, and 49.2% at 900 nm due to the absorption edge of silicon around 0.23  A  /  W, 3.3  ×  1012  cm Hz1/2 W  −  1, and 38.9% at 760 nm due to the absorption edge of P3HT  −  G  /  MoS2 NPS. The results indicate that the PLA method successfully fabricated the P3HT  −  G  /  MoS2 nanocomposites and that the resulting product exhibited high values in responsivity, detectivity, and quantum efficiency. Additionally, it appears that the nanocomposites may have enhanced the same parameters of the PSi photodetector.