22 July 2019
Sensitive and flexible X-ray detection
Published online 7 September 2018
Readily-made, tuneable perovskite nanocrystals light the way to better images.
Perovskite nanocrystals that light up in response to X-rays could be used to build more sensitive, flexible and lightweight medical imaging and X-ray detection systems.
Perovskites are a diverse range of materials that share the same basic crystal structure as the natural perovskite mineral calcium titanate (CaTiO3). Substituting other elements in place of the calcium, titanium and oxygen creates unnatural perovskites with a huge variety of useful properties.
An international team of researchers, including several at King Abdullah University of Science and Technology in Saudi Arabia, developed highly sensitive X-ray-detecting crystals using combinations of caesium, lead and one of three ‘halogen’ elements (chlorine, bromine or iodine). The nanocrystal emissions can be tuned to light up, or scintillate, in different colours in response to the X-rays they absorb.
"We hope this new class of high performance X-ray scintillator can meet tomorrow's increasingly diversified needs," says co-author Liu Xiaogang of the National University of Singapore. "For example, we can develop portable, flexible X-ray imagers for the medical and healthcare industries."
Existing methods to create similar scintillating materials require high temperatures and large crystals, explains Xiaogang. The new method can deposit thin films of tiny nanocrystals onto a flexible plastic substrate from solution, at low temperatures.
Perovskites of many types are being explored for their usefulness in applications including solar cells and light-emitting diodes, but instability in heat and sensitivity to moisture have hindered progress. Xiaogang emphasizes that his team’s X-ray detecting nanocrystals can be protected from such problems by flexible layers of aluminium.
Chen, Q. et al. All-inorganic perovskite nanocrystal scintillators. Nature 561, 88–93 (2018).