Growing special microcrystals for better devices

In an article published in the journal Advanced materialsThe research group of Dr. Atikur Rahman from the physics department of IISER Pune, India, together with collaborators, reports on a new method for growing special crystals called CsPbBr₃ Nanoplatelets.

The excellent properties of these crystals make them promising candidates for use in photodetectors and electronic devices. Research groups of Prof. Pavan Kumar from IISER Pune, Dr. Goutam Sheet from IISER Mohali and Dr. Sooyeon Hwang from Brookhaven National Laboratory, USA, were among those involved in this work.

CsPbBr₃ is a type of material with excellent optoelectronic properties. That is, it can interact with light in ways that are very useful for devices such as solar cells, light-emitting diodes (LEDs), and detectors. These crystals are stable at high temperatures, making them durable and reliable.

However, scientists have so far had problems growing large, high-quality CsPbBr molecules.₃ Crystals with ferroelectric properties and ultra-low dark current. This has limited the use of CsPbBr₃ Crystals in new technologies that could exploit their unique properties, such as optical switches, highly sensitive detectors and advanced solar cells.

In the current work, the team developed a novel method to grow these crystals at room temperature. It is a process called solvothermal synthesis. In this technique, the materials needed to form the crystals are dissolved in a special solution.

“One of the most exciting aspects of this method is that the crystals grown using this method exhibit ferroelectric properties,” said Gokul Anilkumar, a graduate student with Dr. Rahman and lead author of this study.

Ferroelectric materials have the special ability to maintain an electrical polarization that can be reversed by applying an electric field, making them very useful for various advanced technologies.

The researchers used several sophisticated techniques, such as second harmonic generation (a method to test whether the crystals can produce new frequencies of light) and piezoresponse force microscopy (a technique to measure the crystals’ mechanical response to electric fields), to confirm that the crystals are indeed ferroelectric.

By creating microdevices, the researchers tested the electrical conductivity of the crystals and found that they allow very low currents to flow in the dark, meaning they can detect very low levels of light or radiation. These devices are 100 times more sensitive than conventional silicon photodetectors.

Commenting on the potential applications of this development, Dr. Atikur Rahman, who led this collaboration, said: “The ability to grow high-quality CsPbBr₃ Microcrystals are a major advance in materials science. They pave the way for the development of next-generation optoelectronic devices, such as more efficient LEDs and highly sensitive sensors for light and X-rays or other radiation, which could change the way we use and generate energy.”