Fabrication, characterization of the optical and photosensing properties of copper complex nanoplatelets thin films

The ongoing search for materials with desirable properties aligns with the demands of rapid technological advancement, while also prioritizing cost-effectiveness in both material selection and preparation. Therefore, one of the cheapest copper complexes was chosen, which istetraaminecopper (II) sulfate monohydrate. Copper complex thin films were fabricated using spin coating, one of the simplest and most cost-effective methods.The molecular and crystalline structure properties of the prepared films were analyzed and compared to those of their powdered counterparts. Topography analysis via field emission scanning electron microscopy (FE-SEM) showed that the films were composed of nanoplatelets with an average thickness of 50 nm.The optical properties of the prepared films were also examined, using a spectrophotometer focusing on absorption spectra and band gap energy determination.The strong absorption properties are observed in the UV–vis-NIR spectra with a direct energy gap of approximately 2.83 eV.The electrical properties of the copper complex film deposited on p-type silicon were examined under both dark and illuminated conditions to evaluate its potential for photosensing applications. The fabricated heterojunction demonstrated notable sensitivity to changes in the incident illumination power density, with a high photocurrent density of 0.02 A/cm².Additionally, key photosensing parameters including photoresponsivity, specific detectivity, linear dynamic range, and response speed based on rise and fall times were calculated. The fabricated device demonstrated excellent performance, achieving a responsivity of 237.8 mA/W and the capability to detect weak light signals with a specific detectivity of 4.17 × 10⁹ cm·Hz^1/2/W. It also exhibited a linear dynamic range of 13.24 dB and fast response times, with rise and fall times of 38 ms and 226 ms, respectively.A comparison of the performance parameters of the currently prepared device with those from previously published junctions reveals its clear superiority, making it well-suited for photosensor applications.