Fine tuning color coordinate with stacking polymer embedded vertical sparse nanowire arrays for reflective color filter application

Abstract

Multi-color generation have received tremendous attention in recent years with a plenty of applications such as image sensors, optical filters and displays. Till date, the organic pigments and dyes are commonly used materials for obtaining color selectivity via their specific light absorption features, but these materials are vulnerable to external environment such as chemicals and ultraviolet rays. These issues often cause in discoloration and short life span. These shortcomings can be overcome by using inorganic semiconductor based nano-structural color generation, which offers low photo-degradation, high stability and a wide range of color purity compared to conventional techniques. Photonic crystals of vertically oriented silicon nanowire arrays (Si NWAs) have successfully been demonstrated in multi-color generation and color filter applications. The concept of these results open up a wide range of possibilities in reflection/transmission color filter applications. In particular, silicon material is considered as one of the most suitable candidates due to their several notable advantages such as cost, stability and manufacturing processes. Structural colorations from Si NWAs arise due to the interaction of light with the subwavelength structures. Recently, various wave optics based numerical calculations revealed the underlying phenomena, which originates from the leaky, guided, or Bloch modes depending on the density and diameter of the nanowires. The results of wavelength resonant modes from Si NWAs exhibit the strong spectral selectivity dependence on the nanowire geometry. In addition, Si NWAs show a linear combination of reflectance spectra unlike plasmonic nanostructures. Despite the importance of Si NWAs for the optical device applications, there is still a lack of research on various color information systems. In the present work, we design and fabricate a system that is comprised of PDMS and Si NWAs stacked on various thin films which show various colors to provide a straight forward understanding of colorimetric systems with varying silicon nanowire diameter on various substrate such as silver, amorphous silicon and perfect absorber. We also have found that extended gamut in the case of a-Si thin film which shows color variation with different thicknesses. The tunability of colors has been explained on the basis of measured and simulated reflectance spectra.

Recently, photonic crystals of silicon nanowire arrays (Si NWAs) have successfully been demonstrated in multi-color generation and color filter applications. The concept of these results open up a wide range of possibilities in reflection/transmission color filter applications. In particular, silicon material is considered as one of the most suitable candidates due to their several notable advantages such as cost, stability and manufacturing processes. Structural colorations from Si NWAs arise due to the interaction of light with the subwavelength structures. However, various wave optics based numerical calculations revealed the underlying phenomena, which originates from the leaky, guided, or Bloch modes depending on the density and diameter of the nanowires. Wavelength resonant modes from Si NWAs exhibit the strong spectral selectivity dependence on the nanowire geometry. In addition, Si NWAs show a linear combination of reflectance spectra unlike plasmonic nanostructures. Despite the importance of Si NWAs for the optical device applications, there is still a lack of research on various color information systems. In the present work, we design and fabricate a system that is comprised of PDMS and Si NWAs stacked on various thin films which show various colors to provide a straight forward understanding of colorimetric systems with varying silicon nanowire diameter on various colored substrate such as silver, cyan, magenta, yellow. We also have found that extended gamut which shows color variation with different background colors.