New Method Allows Incorporation of Single-Crystal Hybrid Perovskites into Electronics

An international team of scientists have formulated a method that, for the first time, enables single-crystal hybrid perovskite materials to be combined into electronics. Since these perovskites can be synthesized at low temperatures, the advance paves the way to new research into flexible electronics and possibly lower manufacturing costs for electronic devices.

Looking east across campus towards downtown Raleigh on a sunny Spring day. (Photo by Roger Winstead)

Hybrid perovskite materials comprise of both organic and inorganic components and can be synthesized from inks, making them pliable to large-area roll-to-roll fabrication. These materials are the focus of extensive research for use in solar cells, photodetectors, and light-emitting diodes (LEDs). However, there have been difficulties in incorporating single-crystal hybrid perovskites into more classical electronic devices, such as transistors.

Single-crystal hybrid perovskites are better because single-crystalline materials have more appealing properties than polycrystalline materials; polycrystalline materials have more flaws that unfavorably affect a material’s electronic properties.

The challenge in integrating single-crystal hybrid perovskites into electronics stems from the point that these macroscopic crystals, when synthesized using conventional methods, have rough, uneven edges. This makes it hard to combine with other materials in such a way that the materials make the high-quality contacts essential in electronic devices.

The scientists solved this issue by synthesizing the hybrid perovskite crystals between two laminated surfaces, basically forming a single-crystal hybrid perovskite sandwich. The perovskite conforms to the materials below and above, forming in a sharp interface between the materials. The substrate and superstrate, the “bread” in the sandwich, can be any material from glass slides to silicon wafers that are already implanted with electrodes—resulting in a ready-made circuit or transistor.

The scientists can further tweak the electrical properties of the perovskite by choosing various halides for use in the perovskite’s chemical composition. The choice of halide defines the bandgap of the material, which influences the color appearance of the resulting semiconductor and leads to transparent and even undetectable electronic devices when using high-bandgap perovskites.

“We have demonstrated the ability to create working field-effect transistors using single-crystal hybrid perovskite materials fabricated in ambient air,” says Aram Amassian, corresponding author of a paper on the research and an associate professor of materials science and engineering at NC State.

“That’s of interest because traditional single-crystal materials have to be manufactured in ultra-high vacuum, high-temperature environments, and often require exquisite epitaxial growth,” Amassian says. “Hybrid perovskites can be grown from solution, essentially from an ink, in ambient air at temperatures below 100 degrees Celsius.” This makes them appealing from a cost and manufacturing stance. It also makes them well-matched with flexible, plastic-based substrates, meaning that they may be used in flexible electronics and in the internet of things (IoT).

That said, there are still major challenges here. For example, current hybrid perovskites contain lead, which is toxic and therefore not something that’s desirable for applications like wearable electronics. However, research is ongoing to develop hybrid perovskites that don’t contain lead or that are even entirely metal-free. This is an exciting area of research, and we feel this work is a significant step forward for the device integration of these materials, leading to the development of new technological applications.

Aram Amassian, Study Co-Author and Associate Professor of Materials Science and Engineering, NC State

The paper, “Single crystal hybrid perovskite field-effect transistors,” is published in the journal Nature Communications. First co-authors of the paper are Weili Yu, Feng Li and Liyang Yu of the King Abdullah University of Science and Technology (KAUST). The paper was co-authored by Muhammad R.K. Niazi, Daniel Corzo, Aniruddha Basu, Chun Ma, Sukumar Dey, Max L. Tietze, Ulrich Buttner, Xianbin Wang, Zhihong Wang and Mohamed N. Hedhili of KAUST; Yuting Zou, of the The Guo China-US Photonics Laboratory; Chunlei Guo, of The Guo China-US Photonics Laboratory and the University of Rochester; and Tom Wu, of KAUST and the University of New South Wales.

The research was financially supported by KAUST.

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