Perovskite Pattern Formation by Chemical Vapor Deposition Using Photolithographically Defined Templates

Abstract

Thin film fabrication is necessary to realize the device integration of organic–inorganic hybrid perovskites (OIHPs), and solution-based crystallization methods have been employed widely to this end. Despite the versatility of the solution approach, device fabrication using typical “top-down” lithography is generally incompatible with as-prepared OIHPs films because of the low stability of perovskites to polar solvents involved in the lithographic process. Moreover, solution-prepared perovskites usually exhibit irregular surface roughness, implying the existence of randomly oriented crystal domains with a large density of grain boundaries, which are ultimately detrimental to the material properties. Here, we report a patterning of CH3NH3PbI3 (MAPbI3) thin films using a photolithographically fabricated cross-linked copolymer template on Si or SiO2 substrates via a chemical vapor deposition (CVD) method. Perovskite patterning is accomplished by growing PbI2 precursor layers selectively on template patterns and subsequently converting to MAPbI3 using CH3NH3I (MAI) in the vapor phase. We confirm that [0001]-oriented PbI2 nanoplatelets nucleate primarily on a Si or SiO2 surface and grow by surface diffusion from a polymer surface. The MAPbI3 conversion process preserves the original pattern morphology through the vapor–solid intercalation of MAI. Prototype photodetector arrays based on MAPbI3 patterns are also demonstrated. Our results highlight the advantages of the CVD patterning of perovskite materials in large-scale production for a range of optoelectronic applications.

Bromine Doping of MAPbI3 Films Deposited via Chemical Vapor Deposition Enables Efficient and Photo‐Stable Self‐Powered Photodetectors

“…These results indicate a cubic PbI 2 plane at 12.65°, which reveals the decomposition of MAPbI 3 to PbI 2 , in agreement with the literature. [ 17–19 ] The degradation process in films was evaluated further by monitoring the evolution of their Absorption Degradation State (ADS), which is the ratio between the number of solar photons (from AM1.5G illumination) absorbed by the films over time and the number of solar photons absorbed by as‐deposited films. The absorbance of MAPbI 3 films was decreased in the 500–800 nm wavelength range as a function of exposure time (Figure 1d).…”

“…[ 1–3 ] The challenges associated with this solution‐based approach include controlling film formation over large areas, mitigating the effects of non‐uniformity, and overcoming the difficulties of constructing patterned multilayer devices. [ 16–18 ] These factors hamper the device performance and stability and have hindered the commercialization of perovskite‐based optoelectronic devices. [ 16,19 ] To enhance the stability of solution‐processable perovskite solar cells under various stressors (e.g., moisture, light, and temperature), various strategies were explored, such as interfacial engineering via additives, reduction of lattice dimensionality, and mixed cations and halide doping.…”

“…[ 23 ] To overcome the aforementioned challenges in device stability arising from poor film quality, techniques such as chemical vapor deposition (CVD) have been adopted to precisely control morphology, composition, and crystallinity. [ 16–20,23–27 ] Among the mixed‐halide hybrid perovskites, CH 3 NH 3 PbBr x I 3– x has gained a considerable amount of attention due to its enhanced stability and optoelectronic properties, achieved by controlling the Br content in the perovskite films. [ 28–30 ] Seok et al.…”

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.…”

X-ray-Based Spectroscopic Techniques for Characterization of Polymer Nanocomposite Materials at a Molecular Level

“…It is noted that the position is often affected by the conditions of samples and measurements; for example, the accumulation of positive charge upon the photoemission of electrons on an electrically insulated surface, i.e., charging effect, the peak positions are often deviated from the representative values and therefore, calibration by positioning C-C (or C-H) peak in C(1s) region at 285.0 eV is necessary for the peak interpretation. Figure 2 shows a clear emergence of peaks in correspondence to the functionality in a given chemical structure in C(1s) multiplex spectra with an appropriate deconvolution, highlighting the ability to resolve complex chemical structures [50,51]. These analyses have been routinely performed in a number of studies on polymer nanocomposite materials.…”