1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga, Latvia
2. Transport and Telecommunication Institute, LV-1019 Riga, Latvia
3. Department of Technical Physics, L.N. Gumilyov Eurasian National University, Nur-Sultan 010008, Kazakhstan
4. Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
5. College of Sciences & CQUPT-BUL Innovation Institute, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
6. Faculty of Science and Technology, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa, Poland
7. Academy of Romanian Scientists, Ilfov Str. No. 3, 050044 Bucharest, Romania
8. Centre of Excellence for Photoconversion, Vinča Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 11351 Belgrade, Serbia