Improved electrochromic performance of a radio frequency magnetron sputtered NiO thin film with high optical switching speed. Issue 83 (22nd August 2016)

• Record Type: Journal Article
• Authors: Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.; Sathe, Vasant; Ganesan, V.; Wang, T. Y.
• Is Part Of: RSC advances. Volume 6:Issue 83(2016)
• Page Start: 79668
• Page End: 79680
• Publication Date: 2016-08-22
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c5ra27099e
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A nickel oxide (NiO) thin film with better reversibility, high optical modulation, and enhanced coloration efficiency with fast switching time was prepared using radio frequency (rf) magnetron sputtering technique. Abstract : A nickel oxide (NiO) thin film with better reversibility, high optical modulation, and enhanced coloration efficiency with fast switching time was prepared using radio frequency (rf) magnetron sputtering technique. A cubic phase and spherical shaped crystal grain morphology of the NiO film have been determined from structural and surface morphological studies. A micro-Raman study showed two bands around 570 cm −1 and 1100 cm −1 corresponding to the vibrations of Ni–O. An X-ray photoelectron spectroscopic study confirmed the compositional purity and the presence of Ni 2+ and Ni 3+ ions in the film. In addition, the observed transmission threshold at about 368 nm revealed the presence of Ni vacancies or the presence of Ni 3+ ions along with Ni 2+ ions in the deposited film. The photoluminescence peak located at 368 nm in the UV region is attributed to band-edge emission, which may be due to the transition of Ni 2+ ions from the top of the 3d 8 valence band to the bottom of the 3d 8 conduction band. The electrochromic studies reveal an excellent performance with a highest coloration efficiency of 235 cm 2 C −1, reversibility of 64%, optical modulation of 58%, coloration time of 1.2 s and bleaching time of 1.1 s. An electrochemical impedance measurement indicates fast lithium ion transfer with fast switching time, which facilitates the improved electrochromic behavior.