Manipulating the assembly of perovskites onto soft nanoimprinted titanium dioxide templates

Abstract

Soft nanoimprinted titanium dioxide (TiO) substrates decorated with methylammonium lead halide perovskite (MAPbI) crystals were fabricated by controlling the perovskite precursor concentration and volume during spin coat processing combined with the use of hydrophobic TiO templates. The patterned growth was demonstrated with different perovskite crystallization methods. We investigated and successfully demonstrated the controlled assembly of two MAPbI nanomaterials, one a nanocomposite formed between the perovskite and a hole conducting polymer poly(2,5-bis(N-methyl-N-hexylamino)phenylene vinylene) (BAMPPV), and a second formed from perovskite crystals using common solution based MAPbI growth methods (1-step and 2-step processing). Both types of MAPbI crystals were fabricated on hydrophobic TiO nanotemplates composed of nanowells or grating patterns. Patterned areas as large as 100 μm × 100 μm were achieved. We examined and characterized the substrates using atomic force microscopy, scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy. We present the optical properties (i.e. fluorescence and transmission) of soft nanoimprinted nanowells decorated with perovskites demonstrating the successful synthesis of MAPbI perovskite nanocrystals. As an example of their use, we demonstrate a two terminal device and show photocurrent response of a perovskite patterned micro-grating. Our method is a nondestructive approach to nanopatterning perovskites, and produces patterned arrays that maintain their photo-electric properties. The results presented herein suggests an attractive route to developing nanopatterned and small area perovskite substrates for applications in photovoltaics, x-ray sensing/detection, image sensor arrays, and others.

Photonic Structuration of Hybrid Inverse-Opal TiO2—Perovskite Layers for Enhanced Light Absorption in Solar Cells

“…Residues of excess PbI 2 are still noticed but seem inherent of the used spin-coating protocol of perovskite deposition applied to such TiO 2 photoanodes. 60,61 The PbI 2to-CH 3 NH 3 PbI 3 signals have been compared for the different samples, showing no particular impact neither from the occurrence of a porous TiO 2 scaffold nor from the pore dimensions (with PbI 2 -to-CH 3 NH 3 PbI 3 area ratios of ∼0.2 for all samples). In the meantime, perovskite crystallite size values, obtained from Scherrer analysis performed on the 110 peak at 14.1°, tend to increase very slightly with increasing pore Recorded experimental spectra are presented in Figure 3a.…”

Controlling the molecular weight of poly(2,5‐bis[N‐methyl‐N‐hexylamino]phenylene vinylene) using nitrobenzene as an inhibitor

“…In addition, the semi-conducting polymer has been studied as an OLED, 8 and recently, as a polymer scaffold for methyl ammonium lead halide perovskite (MAPbI 3 ) crystals. 22 Unfortunately, like most PPVs, BAM-PPV has low solubility in common organic solvents (often below 1 wt%), which makes the polymer difficult to process and use in large-scale applications. [19][20][21] Two typical approaches to improving PPV solubility are the introduction of solubilizing alkyl groups onto the PPV chain and controlling the molecular weight of the PPV chain during polymerization.…”

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

“…In the literature, both bottom-up and top-down methods have been employed to fabricate a patterned array of perovskites. Bottom-up approaches have been explored, such as printing perovskite patterns through inkjet and roller printing, − or using patterned PDMS molds and packed colloidal spheres for growing perovskite crystals in confined spaces. − Various other templates have also been used, such as anodized aluminum oxide membranes and patterned TiO 2 films for the confined crystallization of perovskite arrays. − Top-down approaches, such as photolithography, e-beam lithography, and atomic force microscopy, have been employed. , Conventional photolithography involves photoresist that is patterned and developed on top of the perovskite layer followed by etching of exposed perovskite thin films. , This method has been modified by prepatterning the substrates followed by spin-coating of perovskite precursors to avoid the step to lift-off the photoresist. − Although these top-down methods provide good quality patterned thin films, several steps involved in the patterning and curing of the photoresist, lift-off, and etching drive up the cost and processing time of fabrication and affect the perovskite properties that jeopardize scaling-up. High-quality, low-cost, and yet simple surface micropatterning techniques are still highly desired.…”