1. Department of Electronics, Communications and Information Technology, Faculty of Physics and Technology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
2. Department of Chemistry, Faculty of Sciences and Arts, and the Nanoscience and Technology Research and Application Center, Canakkale Onsekiz Mart University at Terzioglu, Canakkale, Turkey
3. Department of Physics, Faculty of Physics and Technology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria