Solution‐Processed Aluminum Nanogratings for Wire Grid Polarizers

Abstract

polarized light, the WGP behaves like a metallic mirror, which reflects the incident light because of its high effective extinction coefficient; for transverse magnetic (TM)-mode polarized light, the WGP acts as a dielectric layer, effectively transmitting the incident light. [4] Al is the most commonly used material for WGPs because its refractive indices having low real and high imaginary parts are adequate in providing high TM transmission and TE reflection ( Figure S1, Supporting Information). [4][5][6] Accordingly, the highest performance for both the TM transmittance and extinction ratio (ratio of TM-to TE-mode transmittances) is expected when using Al compared with other metals ( Figure S1g, Supporting Information). Moreover, Al is one of the most abundant metals on earth, low-cost, light-weight, and environmentally stable. Theoretically, an extinction ratio and TM transmittance exceeding 10 000 and 85%, respectively, are expected from sub-100 nm pitch Al WGP. [5,7] To fabricate high-aspect-ratio Al nanostructures, various fabrication processes have been proposed. Especially, nanoimprint lithography, which can produce polymer nanopatterns almost infinitely through repetitive replication from a single master mold, has been widely used. High-aspect-ratio Al nanostructure was formed on the sidewall of a nanoimprinted polymer template by angled metal evaporation and reactive ion etching (RIE). [8][9][10][11] Nanoimprinted polymer resist was also used as an etch mask to create Al nanostructures using RIE. [7,12] However, processes requiring vacuum evaporation and RIE may be insufficiently cost-effective and highthroughput to manufacture Al WGPs. Bottom-up approaches to fabricate WGPs have been attempted, such as colloidal assembly, [13,14] metal-containing block copolymers, [15] and nanowire alignment. [16][17][18] However, the limitations of the material selection and structural versatility caused unsatisfactory WGP performance. Although the formation of metal structures through both electro-and electroless plating has been proposed, a specifically modified template is required for the site-selective growth of metals. [19][20][21][22] For example, hydrophobic or insulating nanostructure was prepared while exposing the hydrophilic or conducting substrate on the bottom portions of the structures, which requires dry etching or photolithography. [19][20][21][22] Moreover, unlike noble metals, the formation of Al nanostructures using solution processes is rare because of the high reactivity of Al with both oxygen and water. Previous studies The wire grid polarizer (WGP) consisting of parallel metal nanogratings is an attractive alternative to conventional polarizers because it offers thin layer thickness, easy integration capability, and outstanding chemical and thermal stability. In this report, a facile solution process is proposed for fabricating Al WGPs. High-aspect-ratio Al nanostructures are formed in a 1D nanoimprinted template by electroless plating. Because of the geometrically irreversible deposition and ...

The role of photon recycling in perovskite light-emitting diodes

“…In the limit of perfect PR and zero parasitic absorption loss, a 100% filter transmission could be achieved for the desired property. Figure 4c-e illustrate more examples of light property optimisation-a 1D metal nanogrid 46,47 that aligns polarisation; an angle confinement microstructure 48,49 , which confines emission angle; and a distributed Bragg reflector 35,50,51 , which narrows both emission angle and spectrum. Polarised emission will be especially useful in display applications, reducing the 50% efficiency losses typically encountered in the circular polariser needed to achieve high contrast ratios.…”

MODs vs. NPs: Vying for the Future of Printed Electronics

“…Lee's solution stamping method of Al metal deposition using nBEA and TTIP has since been used for several applications other than for printed electronics, including for use in antimicrobial and electrostatic pollutant air filters, [130,131] as well as wire grid polarizers. [132] Fei et al used a variation of Lee's process, [133] depositing isopropyl ether stabilised alane (iPEA), [AlH 3 •{O(iPr) 2 }] in the presence of a titanium tetrachloride (TiCl 4 ) reduction catalyst via a solution stamping-process. The best metallic feature was sintered at 80 8C for 30 s to form a 50 nm thick cathode with R s 2.09 W sq À1 and a work function of 3.67 eV.…”

Integrated optical polarizers employing 2D materials

“…Spatial-light optical polarizers can be realized based on various schemes with different device configurations. For instance, wire-grid polarizers utilize finely spaced metallic wires to selectively absorb light in one polarization while allowing the transmission of the other [79]. For sheet polarizers, polarization selection is achieved by absorbing one polarization state more efficiently than the other [80].…”