Water is the secret ingredient in a simple way to create key components for solar cells, X-ray detectors and other optoelectronic devices.
The next generation of photovoltaics, semiconductors and LEDs could be made using perovskites, an exciting and versatile nanomaterial with a crystalline structure.
Perovskites have already shown similar efficiency to silicon, are cheaper to manufacture, and feature an adjustable bandgap, which means the energy they are able to absorb, reflect, or conduct can be changed to meet different objectives.
Usually water is kept as far away as possible during the process of creating perovskites. The presence of moisture can lead to defects in the materials, causing them to fall apart more quickly when used in a device.
This is why perovskites for scientific research are often made by centrifugation in the sealed environment of a nitrogen glove box.
Now, however, members of the ARC Center of Excellence in Excitation Science have found a simple way to control the growth of phase-pure perovskite crystals by harnessing water as a positive factor. This liquid-based mechanism operates at room temperature, so the approach remains cost effective.
Led by researchers at Monash University, the team found that by changing the water-to-solvent ratio during the early stages of the process, they could choose to grow different types of perovskite crystals, with structures suited to various purposes.
Corresponding author Dr. Wenxin Mao of Monash University said: “By carefully adjusting the concentration of water in the precursor solution, we achieved the precise control of particular perovskite phases.”
Computational and thermodynamic analysis conducted by colleagues at the University of Sydney identified that the coordination of lead and bromide ions in the precursor solution was an important factor in determining the types of crystals formed.
Lead author Qingdong Lin, a PhD student at Monash University, said, “We now understand the internal mechanics and function of water inside the precursor solution. By doing so, we can use water more to control the crystallization process.
To demonstrate the quality of the final product, the crystals produced via this approach were coupled to back contact electrodes by nanofabrication to create X-ray detection devices.
This test sample performed at a level similar to commercial X-ray detectors currently used in real-world settings, such as medical imaging and Geiger counters, and outperformed prototype perovskite X-ray detectors developed using slower and more complicated manufacturing methods.
Wenxin said, “We compared them with commercial X-ray detectors as well as other types of perovskites and we have very good X-ray responsiveness and sensitivity. Overall, this project shows that we have found a clever way to control inorganic perovskite. single crystals.
“The methodology is flexible and achievable and does not require a very unique environment or technique to apply it.”
In addition to solar cells, X-ray detectors and LEDs, perovskites created with this method could also be useful in UV light detection, lasers and solar concentrators.