1. Department of Natural Sciences, Phu Yen University, Phu Yen, Vietnam 18 Tran Phu, Tuy Hoa City 56 000, Vietnam
2. Laboratoire de Physique des Interfaces et des Couches Minces (LPICM), Ecole Polytechnique, Palaiseau 91128, France
3. Advanced Display Research Center (ADRC), Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea
4. Energy Materials Laboratory, Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea
5. College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023, Hubei, P. R. China
6. Nanomaterials for Energy Laboratory, Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea