Long‐Range Ordered Crystals of 3D Inorganic–Organic Heterojunctions via Colloidal Lithography

Abstract

Colloidal lithography (CL) has evolved as an alternative to conventional photo‐ and electron‐beam lithography to pattern surfaces with nanometer range resolution. As CL offers substrate‐independent precise positioning and patterning of nanomaterials as long‐range ordered crystals, this has seen new opportunities in optoelectronics. Herein, the scope of CL is expanded to fabricate for the first time, 3D organic–inorganic heterojunction photocatalysts with well‐controlled spacing and coverage density. To achieve this, monodisperse polystyrene (PS) beads of different sizes are used as colloidal masks on a ZnO substrate. Electron beam assisted silver deposition onto these PS masks, and subsequent removal of PS lead to the formation of patterns of silver nanostars on the ZnO thin film. The solid–vapor reaction of silver nanostars with a metal‐coordinating charge‐transfer complex of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) allows spontaneous conversion of Ag nanostars to the large aspect ratio nanowires of metal–organic AgTCNQ semiconductors. This strategy, combining the strengths of CL with high electron affinity of TCNQ molecules allows facile fabrication of long‐range patterns of the heterojunctions of organic (AgTCNQ) and inorganic (ZnO) semiconductors. These surface‐supported 3D heterojunctions act as outstanding photocatalysts through their ability to efficiently separate the electron–hole pairs and thus increasing the electron–hole life times.

Low-Temperature Hydrogen Sensor: Enhanced Performance Enabled through Photoactive Pd-Decorated TiO2 Colloidal Crystals

“…After the surface was dried, the closely packed PS LROC surface was etched by using a plasma cleaner [Gatan model 950, RF 50 W, 10 mTorr, and a 10 standard cubic centimeters (sccm) gas flow for 20 min] under pure oxygen to reduce the PS size and form a uniform nonclosely packed PS LROC surface. The particle size distribution was estimated with an image processing program based on MATLAB reported in our previous work using the Hough transform …”

“…The particle size distribution was estimated with an image processing program based on MATLAB reported in our previous work using the Hough transform. 41 Chemical Vapor Deposition of TiO 2 . The chemical vapor deposition (CVD) reaction explained in our previous work 23 was carried out for 10 min to obtain a thin layer of TiO 2 coating on the PS LROCs.…”

Reaction-Based Scalable Inorganic Patterning on Rigid and Soft Substrates for Photovoltaic Roofs with Minimal Optical Loss and Sustainable Sunlight-Driven-Cleaning Windows

“…Colloids have been used as sacrificial templates to produce inverse opals, − patterns, and nanostructures. − Non-close-packed inorganic colloidal patterns have been created using lithography, sintering, and etching methods. − However, we discovered that inorganic patterns on substrates could be spontaneously formed in a water–methanol mixture containing inorganic precursors when the substrates were coated with a closely packed colloidal monolayer nanosheet (Figure A). The nanosheet was formed on substrates during the evaporation of solvents that were included in the colloids of the closely packed colloidal monolayer.…”

Chemically amplified molecular resins for shrinkage-controlled direct nanoimprint lithography of functional oxides: an application towards dark-light dual-mode antibacterial surfaces

“…1,2 In the past two decades, advancements beyond conventional photolithography and electron-beam lithography have introduced a plethora of fabrication techniques that include dip-pen, nanoimprinting, electro-hydrodynamic, block co-polymer, colloidal, extreme UV and interference lithography. [3][4][5][6][7][8][9][10][11] Among the array of fabrication techniques, nanoimprint lithography has garnered substantial attention due to its distinct advantages such as simplicity, high fidelity, non-dependency on the optical diffraction limit, highthroughput fabrication through step-and-flash or roll-to-roll/ flat and ability to imprint arbitrary structures, even over curved surfaces. [12][13][14][15][16][17][18] While polymeric materials have predominantly been used in these techniques, there has been a recent surge in the direct fabrication of functional inorganic nanomaterials.…”