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

Patterning 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 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^o on octadecane modified FTO surface.