# One‐step Centimeter‐Scale Growth of Sub‐100‐nm Perovskite Single‐Crystal Arrays in Ambient Air for Color Painting

## TL;DR

A new method allows for the rapid growth of tiny, high-quality perovskite crystals in ambient air, enabling large-scale, colorful patterns for optoelectronic devices.

## Contribution

A one-step blade coating method for ambient growth of sub-100 nm perovskite single-crystal arrays on diverse substrates.

## Key findings

- Perovskite single crystals were grown with sizes from 90 to 260 nm and a size variation coefficient <10%.
- RGB color patterns using CsPbX3 perovskites were demonstrated with high photoluminescence quality.
- Crystals were successfully transferred onto flexible substrates like COC.

## Abstract

Halide perovskite single crystals have demonstrated enormous potential for next‐generation integrated optoelectronic devices. However, there is a lack of a facile method to realize the controllable growth of large‐scale, high‐quality, and high‐resolution perovskite single crystal arrays on diverse types of substrates, which hinders their application in practical scenarios. Here, a one‐step wettability‐guided blade coating approach is reported for the rapid in situ crystallization of large‐scale, multicolor, and sub‐100 nm perovskite single‐crystal arrays in the ambient environment. By this strategy, the physical dimensions of perovskite single crystals can be precisely regulated from 90 to 260 nm, with a size variation coefficient < 10% and an area of over 900 mm2. All three typicalhalogen perovskites for multi‐color luminescence, CsPbX3 (X = Cl, Br, I) and their mixtures (Cl/Br or Br/I systems), are appliable to this fabrication process through the demonstration of complex RGB patterns with remarkable photoluminescence properties. Moreover, various rigid substrates such as silicon oxide (SiO2), silicon (Si), and glass can also be used to construct the wettability‐constrast templates where perovskite crystal nucleate and grow. After that, the perovskite single‐crystal arrays or complex patterns can be transferred onto flexible substrates, for instance, COC. This method combines convenient solution processing with conventional photolithography to prepare the high‐resolution, large‐area, and superior‐quality perovskite single crystal arrays in a high‐throughput manner, showing great potential in the integration of perovskite nano‐optoelectronic devices and chips.

Researchers have developed a one‐step wettability‐guided blade coating approach for the rapid in situ crystallization of large‐scale, multicolor, and sub‐100 nm perovskite single‐crystal arrays in the ambient environment. This strategy can be widely extended to various types of halide perovskites and substrates, showing great potential in the integration of perovskite nano‐optoelectronic devices and chips.