ECCS-EPSRC: A new generation of cost-effective, scalable and stable radiation detectors with ultrahigh detectivity

This is a joint effort between a U.S. University (Buffalo) and two U.K. Universities (Cambridge and Oxford).Effectively detecting low dose rates of radiation is critical for improving the safety and capability of non-invasive diagnostics, including medical imaging, nuclear security, and product inspection.

However, current industry-standard materials (namely amorphous selenium and cadmium zinc telluride) have limited ability to detect X-rays, such that the current medical standard X-ray dose rate is a very high value, and this increases the risk of causing cancer. To improve the safety of medical imaging, as well as to improve the effectiveness of a wide range of other diagnostics involving ionizing radiation, it is essential to engineer new materials capable of detecting lower dose rates of radiation, with stable performance under operation.

The collaborative project between the US team (University at Buffalo) and the UK team (University of Oxford and University of Cambridge) is to develop a new generation of cost-effective bismuth-based radiation detectors capable of detecting three orders of magnitude lower dose rates than the current commercial standard. The project will directly address the critical challenge of engineering the materials and the manufacturability for high-performing, operationally stable radiation detectors.

The broader technological impacts of this project are built on collaborations with industry and a US national laboratory. Furthermore, the research program is well integrated with education and outreach programs at all three universities, including: 1) training the future workforce with multidisciplinary research skills in an international research environment; 2) implementing cutting-edge research in novel materials and devices in materials science and engineering curricula through teaching; 3) disseminating research findings to broader audiences through outreach programs; and 4) increasing participation of broad range of groups from local communities, contributing to strengthening and expanding the future STEM workforce in both US and UK and enhancing society awareness of development of state-of-the-art radiation detection technology.

Significantly improved performance of radiation detectors has recently been achieved with lead-halide perovskite single crystals. However, the high lead (Pb) content exceeds the maximum limit set in many jurisdictions (including in the US and UK), and the facile ionic conductivity in these materials limits the range of electric fields that can be applied, thus limiting their operational stability.

This proposal will address the challenges of current X-ray detectors, including the use of toxic elements, limited performance, high manufacturing costs, and limited charge-carrier transport. Our preliminary results have shown that BiOI can be the ideal non-toxic alternative to the Pb-based perovskites for next generation radiation detectors with ultrahigh detectivity because of its heavy elements, large mobility-lifetime products, and high resistivities.

To transfer this technology to industry and to have an impact on medical imaging and nuclear security, we will further 1) improve the mobility-lifetime product to well above 6±2 x 10-2 cm2 V-1 s-1 through compositional engineering, 2) increase the size of the detectors by an order of magnitude (from 5 mm currently) without compromising on performance, and 3) optimize the device architecture and imaging performance. The overall aim of this joint research between US team (University at Buffalo) and the UK team (University of Oxford and University of Cambridge) is to develop a new generation of cost-effective, stable and up-scaled bismuth-based radiation detectors capable of detecting three orders of magnitude lower dose rates than the current commercial standard.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.