ZnO Film UV Photodetector with Enhanced Performance: Heterojunction with CdMoO 4 Microplates and the Hot Electron Injection Effect of Au Nanoparticles

A novel CdMoO 4 –ZnO composite film is prepared by spin‐coating CdMoO 4 microplates on ZnO film and is constructed as a heterojunction photodetector (PD). With an optimized loading amount of CdMoO 4 microplates, this composite film PD achieves a ≈18‐fold higher responsivity than pure ZnO film PD at 5 V bias under 350 nm (0.15 mW cm −2 ) UV light illumination, and its decay time shortens to half of the original value. Furthermore, Au nanoparticles are then deposited to modify the CdMoO 4 –ZnO composite film, and the as‐constructed photodetector with an optimized deposition time of Au nanoparticles yields an approximately two‐fold higher photocurrent under the same condition, and the decay time reduces by half. The introduced CdMoO 4 microplates form type‐II heterojunctions with ZnO film and improve the photoelectric performance. The hot electrons from Au nanoparticles are injected into the CdMoO 4 –ZnO composite film, leading to the increased photocurrent. When the light is off, the Schottky barriers formed between Au nanoparticles and CdMoO 4 –ZnO composite film block the carrier transportation and accelerate the decay process of current. The study on Au‐nanoparticle‐modified CdMoO 4 –ZnO composite film provides a facile method to construct ZnO film based PD with novel structure and high photoelectric performance.