Reusable Chemically Micropatterned Substrates via Sequential Photoinitiated Thiol–Ene Reactions as a Template for Perovskite Thin-Film Microarrays

Abstract

Patterned semiconducting materials are important for many applications such as microelectronics, displays, and photodetectors. Lead halide perovskites are an emerging class of semiconducting materials that can be patterned via solution-based methods. Here we report an all-benchtop patterning strategy by first generating a patterned surface with contrasting wettabilities to organic solvents that have been used in the perovskite precursor solution and then spin-coating the solution onto the patterned surface. The precursor solution only stays in the area with higher affinity (wettability). We applied sequential sunlight-initiated thiol–ene reactions to functionalize (and pattern) both glass and conductive fluorine-doped tin oxide (FTO) transparent glass surfaces. The functionalized surfaces were measured with the solvent contact angles of water and different organic solvents and were further characterized by XPS, selective fluorescence staining, and selective DNA adsorption. By simply spin-coating and baking the perovskite precursor solution on the patterned substrates, we obtained perovskite thin-film microarrays. The spin-coated perovskite arrays were characterized by XRD, AFM, and SEM. We concluded that patterned substrate prepared via sequential sunlight-initiated thiol–ene click reactions is suitable to fabricate perovskite arrays via the benchtop process. In addition, the same patterned substrates can be reused several times until a favorable perovskite microarray is acquired. Among a few conditions we have tested, DMSO solvent and modified FTO surfaces with alternatively carboxylic acid and alkane is the best combination to obtain high-quality perovskite microarrays. The solvent contact angle of DMSO on carboxylic acid-modified FTO surface is nearly zero and 65 ± 3° on an octadecane-modified FTO surface.

Metal Halide Perovskites Functionalized by Patterning Technologies

“…Patterned template‐assisted crystallization of MHPs can create high‐quality nano/microcrystals with perfect surface and homogeneous crystal size. The patterned templates are usually composed of silicon, [ 27,30–33 ] silicon oxide, [ 34 ] alumina, [ 21,35–37 ] 2D materials, [ 38–40 ] and polymer [ 13,26,41–49 ] by the means of photolithography, direct laser writing, focused‐ion‐beam etching, or electron‐beam etching. The perovskite precursor solution is usually dropped on the hydrophilic substrates and confined by hydrophobic patterned molds to create crystal seeds and grow ordered crystal arrays.…”

A Robust Strategy for Photoinitiated Macromolecular Thiol‐Ene Radical Coupling Reaction with High‐Efficiency Based on a RAFT‐Generated Thiol‐Terminated PDPA Reactant

“…[ 6–11 ] So far this kind of reaction has been widely used in many aspects related to organic chemistry, polymer chemistry, and materials chemistry, especially preparation of hydrogels [ 8,12–14 ] and polymer networks, [ 15 ] synthesis of macromolecules, [ 7,16,17 ] coupling of macromolecules, [ 11,18 ] modification of macromolecules, [ 9,19,20 ] and surface modification of materials. [ 21,22 ] More focus with regard to macromolecule synthesis was paid to thiol‐ene polymerization. [ 16,17 ] There are few reports on examples of photoinitiated thiol‐ene radical coupling reaction in constructing macromolecules containing amine moieties like poly(2‐(diisopropylamino) ethyl methacrylate) (PDPA).…”