Nanocomposites and nanomaterials

The optical properties of coated nanoparticles on the substrate by spray pyrolysis
Diachenko O.V.1, Pshenychnyi R.M.2, Shapovalov O.I.1, Kurbatov D.I.1
1 Dept. of Electronics and Computer Technology, Sumy State University, Rymskogo-Korsakova st., 2, Sumy-40007, Ukraine. 
E-mail: alexey.dyachenko@ukr.net
2 Dept. of General Chemistry, Sumy State University, Rymskogo-Korsakova st., 2, Sumy-40007, Ukraine.

Oxide semiconductors are indispensable components in all types of commercialized and emerging thin-film solar cells, widely used as transparent conductive electrodes and buffer layers. Layers based on copper oxide nanoparticles (CuxO) have high air stability, are environmentally friendly and contain in their composition widespread in nature and cheap chemical elements. Therefore, copper oxides are promising for applications as absorption layers when creating solar cells of the 3rd generation.
Basically, for the creation of solar cells on their basis, two phases of this compound CuO and Cu2O are used. CuO is a semiconductor material with a band gap width that varies from 1.30 to 1.44 eV, depending on the conditions of production, whereas Cu2O is a material with the value Eg = (2,0-2,6) еВ. The width of the band gap of the first material corresponds to the Shockley-Queisser optimum, while the Cu2O compound is transparent in the visible region of the spectrum, which makes it possible to create transparent photovoltaic devices.
The copper oxide nanoparticles have synthesized by polyol synthesis, All chemicals have been purchased from Kvalitet (Ukraine) and used as received: copper acetate dihydrate (Cu(CH3CO2)2(H2O)2, 99%), ethylene glycol EG (C2H6O2, 90%), isopropanol (C3H8O, 90%). The resulting nanoparticles were subsequently used for depositing thin layers on transparent substrates by spray pyrolysis.
The study of structural properties and phase composition have performed through X-ray diffraction analysis. The optical properties of copper oxide nanoparticles were investigated using the room temperature optical spectroscopy using the Lasany-722 (India) spectrophotometer in the wavelength range of λ = 350-900 nm. The bandgap energies of CuxO nanocrystals were determined by using a known equation, which is suitable for both direct and indirect band gap materials:

αhν = A(hν-Eg)n