Thin films, big science: FSU chemists expand imaging possibilities with new X-ray material

(Press-News.org) Most people picture a doctor checking for a broken bone when they think of an X-ray. But the technology is just as important in places like airport security, manufacturing, quality control and scientific research, each with its own criteria for size and shape. 

A team led by Florida State University Professor of Chemistry and Biochemistry Biwu Ma has developed a new form for X-ray materials that can meet the needs of large-area applications, changing out complex crystal structures for an adaptable and scalable thin-film detector. The work was published in Angewandte Chemie. 

“We took a material we developed and made it better,” Ma said. “This new form can be made reliably and quickly, giving end users a new way to incorporate X-ray detection in their work.” 

Ma and his group are pioneers of materials known as zero-dimensional organic metal halide hybrids, or 0D OMHHs. These combine organic components, which have a carbon backbone or carbon-hydrogen bond, with inorganic metal halides, which are compounds made from metal and halogen atoms. Their hybrid form allows scientists and engineers to harness the best properties of both components, and they provide low-cost, adjustable and high-performance materials for direct X-ray detection. 

In previous research, the group showed how 0D OMHH single crystals can be used for X-ray detectors. However, their scalability is limited by a slow and complex crystal growth process. 

In this new work, Ma’s team developed amorphous OMHH films, millimeter-thin sheets of organic metal halide hybrids that can be shaped in myriad ways. These films can be readily fabricated into large-area and custom-shaped detectors, enabling broader use in fields such as astronomy, materials science and medical imaging. 

“If a doctor wants to take an X-ray image of someone’s chest, it’s important to have a detector large enough to cover the whole area for an accurate image,” Ma said. “Growing single crystals of that size is extremely difficult. With our new approach and this new amorphous film material, we now have the potential to create much larger and more versatile X-ray detectors for a wide range of applications.”

HOW IT WORKS
0D OMHHs consist of positively charged organic cations ionically bonded to negatively charged metal halide units, forming structures with highly adjustable properties. These materials have already shown promise in applications such as light-emitting diodes, or LEDs, anti-counterfeiting applications and more. 

In this study, the team created amorphous films by combining non-crystalline organic molecules with metal halides, enabling efficient conversion of X-rays into electrical signals for image generation. Like single crystals, the amorphous films also exhibit high-sensitivity, low detection limits and excellent stability, reinforcing their potential to be widely adopted in the construction of detectors.

APPLICATIONS AND FUTURE DIRECTIONS
X-rays are critical in applications ranging from medical diagnostics, including radiography and fluoroscopy, to non-destructive industrial testing, where they are used to inspect welding, detect cracks in materials and examine the integrity of structures. 

Detectors are also used in security. They are in the machines that scan your luggage as you walk through an airport’s screening area, and they’re used to identify hazardous materials in packages sent via mail. They play a crucial role in manufacturing, in uses such as inspecting food products for contaminants. 

Large-area X-ray detectors make imaging easier, enabling higher resolution images, improving detection and allowing for faster throughput of scanned objects. Their ability to cover more area in a single scan is particularly beneficial in industries like cargo inspection, where speed and efficiency are essential. 

“The significance of this work lies in the enabling of possible industrial processing for large-area detection, which is crucial for the material’s applicability,” said Department of Chemistry and Biochemistry chair Wei Yang. “This work is a significant step in a highly innovative effort pioneered by Biwu that showcases the unique strength of our department in this promising area.” 

A provisional patent application titled “Direct X-ray Detectors Based on Solution-Processed Amorphous Zero-Dimensional Organic Metal Halide Hybrid Films” was filed with the U.S. Patent and Trademark Office in April. Ma is also in the process of launching a company with an industry partner to commercialize the technologies developed by his group, including this new way of facilitating X-ray technologies. 

“Since first publishing on these materials almost a decade ago, I have worked with my colleagues to push the boundaries of what they can achieve,” Ma said. “We see 0D OMHHs as versatile and powerful, with the potential to offer a better alternative in many fields.”

COLLABORATORS AND SUPPORT
Additional contributors to this work include chemistry doctoral student Oluwadara Olasupo, the lead author of the publication; other current and former members of Ma’s research group, including Abiodun M. Adewolu, Mohammad Khizr, Tarannuma F. Manny, He Liu, Md S. Islam, Sahel Moslemi, J.S. Raaj V Winfred and Ranjan Das; chemistry professor Yan-Yan Hu; and FSU Ph.D. alumnus Tunde Shonde, now a lecturer in the Department of Chemistry at the University of West Florida. High school student Ethan Kim also participated in this research through FSU’s Young Scholars Program. 

This research was supported by the National Science Foundation and the FSU Office of Research. 

To learn more about Ma’s work and research conducted in the Department of Chemistry and Biochemistry, visit chem.fsu.edu.

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