Ultrafast Light-Controlled Growth of Silver Nanoparticles for Direct Plasmonic Color Printing

Size: px

Start display at page:

Download "Ultrafast Light-Controlled Growth of Silver Nanoparticles for Direct Plasmonic Color Printing"

Rosalind Garrison
5 years ago
Views:

1 Supporting Materials for Ultrafast Light-Controlled Growth of Silver Nanoparticles for Direct Plasmonic Color Printing Yangxi Zhang, Qiang Zhang, Xia Ouyang, Dang Yuan Lei, A. Ping Zhang * and Hwa-Yaw Tam Photonics Research Center, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China. Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China. * azhang@polyu.edu.hk. The PDF file includes: Figure S1. Characterization of printing resolutions with respect to nanoparticles of different expected sizes. Table S1. Ellipsometric measurement results of the titanium dioxide layers on quartz substrates. Figure S2. Printed color images without the use of PVP. Figure S3. Spectral responses of the samples printed without the use of PVP and the FSEM images of corresponding silver nanoparticles. Figure S4. Particle-size distribution of the silver nanoparticles. Figure S5. Numerical study of the effects of TiO2 thickness on reflection spectra. Figure S6. Collection of printed plasmonic color images. Figure S7. Effective refractive indices of the media surrounding silver nanoparticles. Figure S8. Comparison of the printed color images before and after fourteen months of storage. Figure S9. Comparison between the two groups of colors printed on substrates with amorphous-phase and anatase-phase TiO2 layers. 1

Figure S1. Characterization of printing resolutions with respect to nanoparticles of different expected sizes. (A) Line-shape optical pattern for resolution testing.

2 Figure S1. Characterization of printing resolutions with respect to nanoparticles of different expected sizes. (A) Line-shape optical pattern for resolution testing. (B) SEM images of the AgNP patterns fabricated with different exposure doses. The average sizes of AgNPs in the figures (i), (ii), (iii) and (iv) are 17.02, 22.87, 36.61, and nm, respectively. The testing was carried out in a high-resolution DMD-based digital UV exposure setup, whose theoretical optical resolution is µm. The 0.88-µm wide line-shape optical pattern was generated by using a three-pixel wide line-shape image. 2

3 Table S1. Ellipsometric measurement results of the titanium dioxide layers on quartz substrates Substrate No. S1 S2 S3 S4 S5 Polybutyl titanate concentrations 2 wt% 4 wt% 6 wt% 8 wt% 10 wt% Thickness Refractive index 532 nm Exceeded detection range Exceeded detection range 28.7 nm 39.9 nm 58.9 nm 73.3 nm

(B) The color palette summarizes all colors generated by different fabrication conditions.

4 Figure S2. Printed color images without the use of PVP. (A) The color images of Hong Kong bauhinias printed by using different substrates and exposure times. (B) The color palette summarizes all colors generated by different fabrication conditions. The printing process was conducted with the fabrication conditions exactly the same as that used to print the samples shown in Fig. 2A and 2B except not use of PVP. The results show that the colors of those samples are with lower saturation and brightness. 4

Figure S3. Spectral responses of the samples printed without the use of PVP and the FSEM images of corresponding silver nanoparticles. (A) Reflection spectra of the samples without use of PVP.

5 Figure S3. Spectral responses of the samples printed without the use of PVP and the FSEM images of corresponding silver nanoparticles. (A) Reflection spectra of the samples without use of PVP. (B) FSEM images of the samples. The expose doses for printing the samples increase from 1.11 J/mm 2 to 5.53 J/mm 2. It can be seen that the reflection dips of those spectra are obviously broader than those shown in Fig. 3A. Correspondingly, the nanoparticles shown in Fig. S3B are more variegated and less uniform than those shown in Fig. 3B. 5

6 Figure S4. Particle-size distributions of the silver nanoparticles shown in Fig. 3. The results are fitted with log-normal distributions. It can be seen that the size of nanoparticles is 33 ~ 59 nm when the exposure dose is low, see Fig. S4 (i)-(iv). The standard deviations of the distributions are small, which indicates uniform size of particles. When the exposure dose increases, the nanoparticles grow to 70 ~ 100 nm, see Fig. S4 (v)-(viii). Meanwhile, the standard deviations become much larger (increase from 8.85 nm to nm), which indicates the generation of varied nanoparticles. (EV: expected value; SD: standard deviation) 6

7 Figure S5. Numerical study of the effects of TiO2 thickness on reflection spectra. The nanoparticles of the silver nanoparticle-tio2-quartz structure are chosen with the geometric parameter (50 nm, 30 nm). The permittivity of TiO2 was obtained from the experimentally measured data (see the Substrate preparation section). It can be seen that a reflection dip appears in the visible region and shifts toward longer wavelength with the increase of the thickness of TiO2 layer. The results agree well with the observation of the colors change from yellow to violet to blue with the increase of the thickness of TiO2 layer from the substrate S1 to S5 in Fig. 2 and Fig. S2. 7

Figure S6. Collection of printed plasmonic color images. (A) Three color images of campus buildings printed by using different exposure doses. (B) Printed Hong Kong bauhinia flower.

8 Figure S6. Collection of printed plasmonic color images. (A) Three color images of campus buildings printed by using different exposure doses. (B) Printed Hong Kong bauhinia flower. (C, D) Printed logo (permission obtained from The Hong Kong Polytechnic University) and abbreviated name of The Hong Kong Polytechnic University, respectively. (E) Printed Hong Kong city skyline. All color images were printed on the substrate S5. 8

9 Figure S7. Estimation of the effective refractive indices of the media surrounding silver nanoparticles. The red dots in the figure show the measured wavelengths of the spectral dip (denoted asλ dip ) with respect to the refractive indices of the media (i.e., nmd), when a printed sample (shown in Fig. 5B) was immersed into water, glycol water solution and limonene, sequentially. It can be seen that the spectral dip shifted toward longer wavelength with the increase of the refractive index. The spectral response of the sample in the three liquids is almost linear, which can be well fitted by using λ dip = n md, where the refractive indices n md of the water, glycol water solution and limonene are known as 1.33, 1.4 and 1.47, respectively. However, the measured spectral response becomes nonlinear if the wavelength of the spectral dip of the sample in air is included. The potential cause of such nonlinearity is that some nanoscale air bubbles exist around silver nanoparticles and make the effective refractive index (i.e., neff) of the media surrounding nanoparticles lower than that of the liquid itself. Here, we use a simplified model to translate the measured spectral response toward shorter wavelength to make it go through the wavelength of the spectral dip in air and hereby obtain the effective refractive indices of surround media. The effective refractive indices estimated from such a model are 1.182, 1.256, and 1.322, which were used to numerically simulate the spectral responses of the silver nanoparticle-tio2-quartz structure in different media in Fig. 5C. 9

Figure S8. Comparison of the printed color images before and after fourteen months of storage. (A) Color images produced on April 27, 2017.

10 Figure S8. Comparison of the printed color images before and after fourteen months of storage. (A) Color images produced on April 27, (B) Color images of the sample after stored for fourteen months (photographed on June 21, 2018). The sample was placed inside an unsealed plastic petri dish in dark environment of a laboratory whose room temperate and humidity are 23 ~ 25 C and 40 ~ 60 %RH, respectively. 10

11 Figure S9. Comparison between the two groups of colors printed on substrates with amorphous-phase and anatase-phase TiO2 layers. (A) Color image of the samples printed on the substrate with amorphous-phase TiO2 layer. (B) Color image of the samples printed on the substrate with anatase-phase TiO2 layer. 11

Printing Beyond srgb Color Gamut by. Mimicking Silicon Nanostructures in Free-Space

Supporting Information for: Printing Beyond srgb Color Gamut by Mimicking Silicon Nanostructures in Free-Space Zhaogang Dong 1, Jinfa Ho 1, Ye Feng Yu 2, Yuan Hsing Fu 2, Ramón Paniagua-Dominguez 2, Sihao