Organic-inorganic hybrid perovskite has a strong appeal in many device applications due to its unique electronic and optoelectronic properties. Although many methods focus on polycrystalline perovskite materials, due to the directional transport behavior and lower defect concentration of single-crystal hybrid perovskites, its carrier transport performance and stability are better than polycrystalline materials. However, the preparation of single crystal perovskite and the control of its morphology and composition are challenging.

To this end, Professor Xu Sheng’s team at the University of California, San Diego reported a solution-based printing-assisted epitaxial growth and transfer method to prepare single-crystal hybrid perovskites on flexible substrates bent at any angle, and can precisely control single crystals. Perovskite thickness (600 nm~100 μm), area (continuous film area up to 5.5 cm×5.5 cm) and composition gradient in the thickness direction (from MAPbI3 to MAPb0.5Sn0.5I3).
The transferred single-crystal hybrid perovskite has the same quality as directly grown on the epitaxial substrate, and has mechanical flexibility depending on the thickness. The lead-tin gradient alloying can form a gradient electronic band gap, thereby increasing carrier mobility and hindering carrier recombination. Single-crystal hybrid perovskite devices not only show high stability to various degradation factors, but also have good performance (for example, the average efficiency of solar cells based on lead-tin gradient structure is 18.77%).
The relevant results were published in Nature on July 29, 2020 under the title "A fabrication process for flexible single-crystal perovskite devices".

Graphic guide

Figure 1: Print-assisted epitaxial growth and transfer method to prepare high-quality single crystal hybrid perovskite film.

Figure 2: Carrier transport and mechanical properties related to the thickness of single crystal hybrid perovskite

Figure 3: Gradient band gap of single crystal perovskite film.

Figure 4: Single crystal perovskite solar cell device with flexible gradient band gap
Literature information
A fabrication process for flexible single-crystal perovskite devices
https://www.nature.com/articles/s41586-020-2526-z
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