Authors: Madhavi Sharad Darekar | Praveen Beekanahalli Mokshanatha
Source: Journal of Modern Nanotechnology (article, 2025-11-04)
Field: Materials Science — Materials Chemistry

Analyzing the Impact of Dopants on the Physical and Optical Characteristics of Nanomaterials Objective: This study highlights the contrasting experimental outcomes of undoped and doped nanoparticles and thin films, emphasizing the advantages of doped materials in various applications over their undoped counterparts. Specifically, it aims to demonstrate the enhanced performance and suitability of doped materials in diverse settings. Method: The study involved the synthesis of Thioglycerol-capped undoped cadmium sulphide (CdS) and copper sulphide (Cu2S) nanoparticles, and Mn-doped diluted magnetic semiconductor (DMS) CdS and Cu2S nanoparticles using a room-temperature, non-aqueous chemical method. Undoped CdS and Cu2S thin films, Mn-doped CdS, and Cu2S thin films were fabricated on fluorine-doped tin oxide (FTO) glass substrates via dip coating, followed by annealing at 420°C in air for 20 minutes. The optical properties of CdS, Cu2S, CdS:Mn, and Cu2S:Mn nanoparticles were investigated using Ultraviolet-Visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy. Energy Dispersive X-ray Analysis (EDAX) was employed to determine the chemical composition of undoped CdS and Cu2S and Mn-doped CdS and Cu2S thin films and the FTO glass substrates, with chemical composition percentages determined using mapping techniques. Results: A blue shift was observed in the optical absorption spectra of CdS and Mn-doped CdS nanoparticles. This phenomenon was attributed to quantum confinement effects. Doping the CdS nanoparticles led to a significant enhancement in their average size. Mn doping in CdS nanoparticles significantly boosts their photocatalytic activity and other performance aspects compared to undoped CdS by altering their optical and structural properties, which results in larger particle sizes, improved light absorption, and increased electron-hole separation, making them more effective for applications in solar cells and environmental remediation. In the same way, the UV-Vis absorption spectra of Mn-doped Cu2S nanoparticles also exhibited a blue shift, mirroring the observation in the undoped Cu2S nanoparticles. In UV-Vis absorption spectra, Mn doping in CdS and Cu2S results in a red shift and broadening of absorption bands, which indicates larger particle sizes for the doped nanoparticles compared to their undoped counterparts. This effect stems from doping's influence on the electronic structure, creating new energy levels and absorption bands within the material's band gap, leading to enhanced light absorption and thus suitability for applications like optoelectronics and photocatalysis. The photoluminescence spectra of pure CdS nanoparticles showed a blue-shifted peak, while the Mn-doped CdS nanoparticles displayed a red-shifted peak. The PL emission peak for both pristine and Mn-doped Cu2S nanoparticles was observed at shorter wavelengths, indicating a blue shift. EDAX analysis confirmed a 1:1 atomic ratio of Cd to S, indicating stoichiometric CdS thin film formation. A 2:1 atomic ratio of copper to sulfur was observed via EDAX, confirming the stoichiometric Cu₂S composition of the film. The structural information obtained from X-ray diffraction (XRD) was further enriched by Scanning Electron Microscopy (SEM) analysis, which elucidated the surface morphology and roughness. Conclusion: The experimental findings presented here reveal that doping CdS and Cu2S nanomaterials and thin films leads to significant improvements, demonstrating their enhanced suitability for a variety of technological applications over undoped versions. Doping ; Nanomaterials ; Nanoparticle ; Thin film ; Photoluminescence ; Dopant ; Annealing (glass) ; Quantum dot ; Tin oxide Quantum Dots Synthesis And Properties ; Laser-Ablation Synthesis of Nanoparticles ; Chemical and Physical Properties of Materials