Solid-state synthesis and effect of temperature on optical properties of Cu–ZnO, Cu–CdO and CuO nanoparticles

• Published in: Powder technology Vol. 214; no. 3; pp. 337 - 343
• Main Authors: Vidyasagar, C.C., Naik, Y. Arthoba, Venkatesh, T.G., Viswanatha, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-12-2011; Elsevier
• Subjects: absorbance; absorption; annealing; ANNEALING PROCESSES; Applied sciences; Band gap; chemical composition; Chemical engineering; chemical reactions; Copper; COPPER OXIDE; crystal structure; crystals; CuO; cupric oxide; Cu–CdO; Cu–ZnO; DOPING; energy; Exact sciences and technology; FABRICATION; Grinding; MICROSTRUCTURES; Miscellaneous; Nanoparticles; Nanostructure; OPTICAL PROPERTIES; PARTICLES; Photovoltaic cells; polyethylene glycol; Polyethylene glycol 400; Reactors; scanning electron microscopy; semiconductors; SOLAR CELLS; Solid-solid systems; Solid-state reaction; Synthesis; temperature; X-ray diffraction; ZINC OXIDE; Cu–ZnO; Solid-state reaction; Band gap; CuO; Polyethylene glycol 400; Cu–CdO; Scanning electron microscopy; Annealing; Nanoparticle; Doping; Grinding(comminution); Temperature effect; Cu-CdO; Crystallinity; Dispersive spectrometry; X ray diffraction; Ultraviolet radiation; Chemical reaction; Morphology; Optical properties; Preparation; Solid state reaction; Chemical composition; Cu-ZnO; Nanostructured materials
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2011.08.025

Controlling novel morphologies and developing effective doping strategies are two important tasks for advancing ZnO and CdO based nanomaterials. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiencies of the solar cell. The P-type semiconductors of copper oxide and zinc oxide are an important functional material used for photovoltaic cells. CuO is attractive as a selective solar absorber since it has high solar absorbance and a low thermal emittance. This work describes the synthesis and characterization of semiconducting nanoparticles (ZnO, CuO, CdO, Cu–ZnO, Cu–CdO) via one-step, solid-state reaction in the presence of polyethylene glycol 400.
Solid-state mechanochemical processing—which is not only a physical size reduction process in conventional grinding but also a chemical reaction that is mechanically activated at the nanoscale during grinding. The present method is a simple and efficient method for the preparation of nanoparticles with high yield at low cost. The structural and chemical composition of the nanoparticles were analyzed by X-ray diffraction, field emission scanning electron microscopy and energy-dispersive spectrometer (FESEM/EDAX). Optical properties and band gap were studied by UV–vis absorption spectra. XRD data has been concluded that the Cu doping induced the lattice constants to change to some extent. These results have showed that the band gap energy decreases with increase in annealing temperature, which can be attributed to the improvement in crystallinity of the samples. The band gap of the Cu–ZnO and Cu–CdO crystals can be tuned in the range of 3.34–3.28eV and 2.80–2.21eV respectively, by the use of dopants.
The effects of temperature on optical properties of Cu-doped nanoparticles which were successfully synthesized using suitable surfactant. Fig. A shows typical FESEM images of the CuO crystals. The red shift of 107.8nm in the Cu-doped sample indicates a reduction of CdO band gap caused by the Cu doping (Fig. B). [Display omitted]
► Undoped and Cu-doped nanoparticles have been synthesized using PEG 400. ► The effect of temperature on the structure and optical properties was studied. ► The intensity of peaks and crystanillity were increased with increase in temperature. ► The optical band gaps were decreased. ► Modulation of band energies offers new ways to improve efficiency of the solar cell.