外文翻译：溶胶—凝胶法沉积氧化镍薄膜的电致变色性能

Electrochromic performance of solgel deposited NiO thin fi lm Dhanaji S. Dalavi a, Rupesh S. Devanb, Raghunath S. Patilc, Yuan-Ron Mab, Pramod S. Patila,n aThin Films Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, MS, India bDepartment of Physics, National Dong Hwa University, Hualien 97401, Taiwan cDepartment of Physics, The New College, Kolhapur 416012, India a r t i c l e i n f o Article history: Received 2 August 2012 Accepted 25 August 2012 Available online 3 September 2012 Keywords: Nickel oxide Smart windows a b s t r a c t The nickel oxide (NiO) fi lms were prepared from nickel acetate precursor by solgel dip coating technique. The fi lms were characterized for their structural, compositional, morphological, optical, electrochromical and colorimetric measurement using X-ray photoelectron spectroscopy, scanning electron microscopy, cyclic voltammetry, optical transmittance studies and CIE system of colorimetric analysis. XPS measurements revealed that the fi lms exhibited presence of NiO phase. SEM images showed a smooth and porous nature of NiO thin fi lm. The EC device made up of glass/ITO/NiO/KOH/ITO/ glass showed optical modulation of 51% and relative luminance difference of 49.45%, respectively. In addition to the aforementioned parameters, the coloration effi ciency was found to be 49 cm2/C at 550 nm. fax: 91 231 2691533. E-mail address: psp_phyunishivaji.ac.in (P.S. Patil). Materials Letters 90 (2013) 6063 The energy separation of 17.58 eV observed between Ni (2p3/2) and Ni (2p1/2) peaks assigned to NiO, which is in well agreement with the earlier reports 10. The O-1s XPS spectrum of NiO fi lm showed in Fig. 1(b) is deconvoluted into three peaks located at 529, 530.97 and 532.23 eV, respectively. The high intense peak located at BE of 530.97 eV with shoulder peak at 529 eV corre- sponds to the O-1s core level of the O2anions in the NiO. The higher binding energy peak at 532.23 eV corresponds to the surface contamination 11 such as carbon oxides, and H-O-H bond for the residual water 12. This again confi rms that the NiO thin fi lm is composed of pure stoichiometric NiO phase. The scanning electron micrograph images of NiO thin fi lm are shown in Fig. 2(a,b). It was observed that though the surface seems to be compact and smooth at lower magnifi cation, it is a porous network of micro granules at higher magnifi cation which is benefi cial for electrolyte penetration into the fi lm structure which causes the enhancement in the electrochromic perfor- mance. Fig. 3 presents the cyclic voltammogram of the NiO thin fi lm, which was recorded for fi rst fi ve cycles at 50 mV/s in 1 M KOH electrolyte with linear potential sweep between 71 V vs. SCE. During the anodic scan, intercalation of OH-ions leads to 850855860865870875880885890 Intensity (A.U.) Ni(2p)1/2 Ni(2p)3/2 6.01 eV 17.58 eV 5.51 eV 879.04 873.03 866.68 860.96 855.45 Binding energy (eV) 527 528 529 530 531 532 533 534 535 536 537 Intensity (A.U.) O1s 532.23 530.97 529.00 Binding energy (eV) Fig. 1. (a) The high resolution XPS core level spectra of Ni (2p) and (b) O (1s). Fig. 2. SEM images of NiO thin fi lm at (a) 15,000 X and (b) 20,000 X magnifi cation. Fig. 3. Cyclic voltammogram for solgel deposited NiO thin fi lm. 3004005006007008009001000 1100 0 10 20 30 40 50 60 70 80 90 100 Colored Bleached T=51% Transmittance (%T) Wavelength (nm) Fig. 4. Optical transmission spectra of a glass/ITO/NiO/KOH/ITO/Glass EC device showing colored (1 V) and bleached (?1 V) states. D.S. Dalavi et al. / Materials Letters 90 (2013) 606361 oxidation of Ni2to Ni3 resulted in brown color NiO fi lm. However, during the cathodic scan, deintercalation of OH-ions follows reduction of Ni3to Ni2 and NiO fi lm became transpar- ent again and is represented by following equation 13; NiO transparentzOH?2NiOOH dark brown ze?1 Fig. 4 shows the optical transmission spectra of NiO thin fi lm in its colored and bleached state, in the wavelength range 3001100 nm. The optical transmittance difference is found to be 51% at 550 nm. Thus the fi lm nanoporous morphology pro- vides the suitable conduits for intercalation/deintercalation of OH?ions. The CE (Z) determines the amount of optical density change (DOD) as a function of the injected/ejected electronic charge (Qi) at a specifi c wavelength, i.e., the amount of charge required for changing the optical density. It is given by Z DOD Qi ? l 550 nm lnTb=Tc Qi ? 2 where Tband Tcis the transmittance in the bleached and colored state. The CE of the solgel deposited NiO thin fi lm was found to be 49 cm2/C, which is higher than that earlier report 14. The improved CE may be attributed to the larger textural boundaries and larger active surface area, where actual coloration/bleaching processes take place. A two-dimensional x?y representation known as the chroma- ticity diagram utilized to identify the colors of NiO thin fi lm in its oxidation and reduction state are shown in Fig. 5(a,b). The shift in x?y co-ordinates occurs once the potential switched from reduction to oxidation state. The shift in x?y co-ordinates illustrates that, the color of the NiO immensely changes from highly transmittive (bleached) state to deep brown state. In the CIE 1931 Yxy color space, the tristimulus value Y is defi ned as a measure of the brightness or luminance of the color as shown in Fig.5(b). It is observed that relative luminance (% Y) changes from 30.93% (colored) to 80.38% (bleached) indicating having luminous transmittance difference (Y) of 49.45%. 4. Conclusions Solgel deposited NiO fi lms were successfully grown from sols of nickel acetate. The NiO phase formation is confi rmed XPS studies. The morphological studies revealed that the fi lm com- posed of porous micro granules which serve as conduits for effective electrolyte access into the fi lm structure that can be helpful for the augmenting the optical modulation of 51% and CE of 49 cm2/C at 550 nm. The chromaticity measurements showed a luminous transmittance difference of about 49.45%. Table 1 Acknowledgment One of the authors Mr. D.S. Dalavi is thankful to University Grants Commission (UGC) for the award of Rajiv Gandhi Senior Research Fellowship F. No. 16-1225 (SC)/2008 (SA-III). References 1 Granqvist CG. Adv Mater 2003;15:1789803. 2 Avendano E, Erggren L, Niklasson GA, Granqvist CG, Azens A. Thin Solid Films 2006;496:306. 3 Dalavi DS, Suryavanshi MJ, Patil DS, Mali SS, Mohalkar AV, Kalagi SS, et al. Appl Surf Sci 2011;257:264756. 4 Dalavi DS, Suryavanshi MJ, Mali SS, Patil DS, Patil PS. J Solid State Electrochem 2012;16:25363. 5 Atkinson A. Corrosion Sci 1982;22:34757. 6 Sato H, Minami T, Takata S, Yamada T. Thin Solid Films 1993;236:2731. Fig. 5. (a) CIE 1931 Yxy chromaticity diagram for 21 observer and D-65 illuminant and (b) relative luminance vs. applied potential for NiO thin fi lm in its colored and bleached states. Table 1 parameters evaluated for NiO thin fi lms synthesized solgel technique. Anodic potential (mV/s) Cathodic potential (mV/s) Anodic peak current (mA/cm2) Cathodic peak current (mA/cm2) Transmittance (%T) Transmittance difference (DT %) Optical density (DOD) Coloration