On Structural Color Films By Adjustments Of Materials Combination&Dielectric Layer Thickness

Due to the better chemical stability,more reliable durability,and quite richer color series that could be obtained by adjustments of materials combinations&scales of the dielectric layers than the intrinsic color films,the structural color films have a promising potential for appearance color rendering applications such as consumer electronics.However,up to now,there are still some technical obstacles and property shortages impeding their large-scale industrial applications,including their low color saturation caused by excessive F WHM of the characteristic reflection,and their questionable servicing reliability caused by the quite strict limitation in film thickness to fulfill the requirements of the constructive interference.To overcome those problems,this thesis tried to focus on the interference design criteria as a breakthrough point.Through theoretical simulation&experimental investigation,the different effects of the ?/4 and the 3?/4 design criteria on the dielectric layer thickness and the reflection spectral characteristics of structural color films were compared and the influences of the design criteria,dielectric layer materials and dielectric layer thicknesses on servicing reliability of the prepared structural color films were also experimentally evaluated.Based on effective increasing of the thicknesses of dielectric layers&the whole films and the decreasing of the variation ratios of the dielectric layer thickness fluctuation to their design scales,the dielectric layers with gradient thickness were successfully prepared by a simple substrate tilting device.As a consequent result,the structural color films with better optical performance,more reliable servicing durability,and controllable gradient color appearances were finally obtained.The results of this research are concluded as follows:1.The interference order(k)has significant effects on the FWHM of characteristic reflections and the dielectric layer thicknesses of the H-L combination multi-level interference structural color films.Compared to the condition when the ?/4 criterion was adopted,not only the dielectric layer thicknesses could increase about 3 times and the overall film thicknesses could reach to a higher than 1.0 ?m level,but the FWHM of the characteristic interference refelction peak of the structural color films with different designed center wavelengthes could also significantly decrease by 67.46?69.20%under the condition of the 3?/4 design criterion was adopted.It reveals that using the 3?/4 interference criterion to design&prepare structural color films has the theoretical feasibility to effectively increase the overall film thickness and to improve the color rendering performance of the structural color films.2.Compared to the condition when the ?/4 criterion was adopted,the prepared two kinds of structural color films based upon the 3?/4 criterion with different dielectric layer material combinations reveal much better optical performance that match the previous theoretical simulation results.At different center wavelengthes,their FWHMs of characteristic refelction peaks decrease correspondingly by 58.33?72.17%while their reflectances only slightly decrease by 0.24?17.12%.When the center wavelength was set to a same value,compared to the A12O3-TiO2 films,the SiO2-TiO2 films show approximate FWHMs but reasonably higher reflectivity and color rendering brightness.This implies that the material combination of the dielectric layers could hardly change the monochromaticity of the prepared structural color films but principally influence their reflectivity.3.When the 3?/4 criterion was adopted,the bonding forces of the prepared films could effectively improve by 4?5 levels compared with the films prepared by the condition when the?/4 criterion was adopted.This might be caused by the sufficient increases in thicknesses of both the individual dielectric layers and the whole films.At the same time,the design criteria show the same effect on the corrosion resistance of SiO2-TiO2 and Al2O3-TiO2 films,and the corrosion resistance of the film is better under the 3?/4 design criterion.Experimental results also show that the effects of different design criteria,material combinations and dielectric layer thickness parameters on the wear resistance of the prepared structural color films are quite indistinctive,and all of them appeared acceptable wear resistances that fulfill the industrial YD/T 1539-2006 testing standard of the electronic product.4.Under the conditions while the 3?/4 criterion was adopted,the substrate deflection could effectively result in thickness gradient of the dielectric layers in deposited SiO2-TiO2 films,and then an apparent gradual chromatographic color distribution at different segmented areas of the'same' sample.The mechanism of this phenomenon mainly caused by the position-related thickness differences in dielectric layers that generated by changes of the real target-substrate distances induced by the variation of tilting angles which the substrates are set to.By using a simple supporting pad device,the tilting angles(?)of segmented samples with a 0°?20° range could be experimentally realized in the film deposition processes.Experiment results show that the larger ? caused the steeper thickness gredient in the dielectric layers,and consequently,the variation range of the SiO2 layers and the TiO2 layers could approach-5?+75 nm and-4?+48 nm,respectively.The increases in ? and in position offset principally result in the 'red' shift effect of the center wavelength of characteristic refelction peaks at different locations of the deposited films on the 'same' sample.Compared to the untilted samples,the variation range of the center wavelength at different film locations of the tilted samples could approach 458(-10?+116)nm,and then generate apparent surface gradient colored effects.In conclusion,by using RF-DC reactive co-sputtering and adoption of the 3?/4 interference design criterion,structural color films with better optical performance and service reliability than conventional ?/4 design criterion could be successfully prepared.At this basis,the thickness gradient of the dielectric layers in deposited films and corresponding surface gradient color effects could be achieved by introducing and appropriate adjustment of a simple sample tilting device.