Towards high loading cesium lead halide nanocomposites for radiation detection

Abstract

Cesium lead halide nanocrystals (NCs) and their nanocomposites have attracted a lot of attention in the field of radiation detection thanks to their excellent luminescent properties, especially their potential for fast timing. However, most research on their nanocomposites focuses on low loadings (around 1 wt%) which is insufficient for detecting high-energy X-rays or gamma-rays. There have been only few reports exploring materials with higher loadings but all with limited success in terms of transparency of the final material. In our work, we present nanocomposites of cesium lead halide NCs with loading up to 40 wt%. We employ innovative surface functionalization of the NCs to enhance their dispersion within the matrix, thereby improving the final material transparency. We display the NC dispersion within the matrix using confocal photoluminescence microscopy and we then characterise the radioluminescent properties of nanocomposites of cesium lead bromide (CPB) and cesium lead bromochloride NCs with varying chloride content. To asses their performance as radiation detectors, we measure their timing capabilities under X-rays. Our findings reveal a significant improvement in time resolution under X-rays from previously published 300 ps for CPB polymer nanocomposites to 215 ps. When combined with increased stopping power of high NC content, this advancement holds great promise for practical applications, e.g. in time-of-flight positron emission tomography and computed tomography or high energy physics.Cesium lead halide nanocrystals (NCs) and their nanocomposites have attracted a lot of attention in the field of radiation detection thanks to their excellent luminescent properties, especially their potential for fast timing. However, most research on their nanocomposites focuses on low loadings (around 1 wt%) which is insufficient for detecting high-energy X-rays or gamma-rays. There have been only few reports exploring materials with higher loadings but all with limited success in terms of transparency of the final material. In our work, we present nanocomposites of cesium lead halide NCs with loading up to 40 wt%. We employ innovative surface functionalization of the NCs to enhance their dispersion within the matrix, thereby improving the final material transparency. We display the NC dispersion within the matrix using confocal photoluminescence microscopy and we then characterise the radioluminescent properties of nanocomposites of cesium lead bromide (CPB) and cesium lead bromochloride NCs with varying chloride content. To asses their performance as radiation detectors, we measure their timing capabilities under X-rays. Our findings reveal a significant improvement in time resolution under X-rays from previously published 300 ps for CPB polymer nanocomposites to 215 ps. When combined with increased stopping power of high NC content, this advancement holds great promise for practical applications, e.g. in time-of-flight positron emission tomography and computed tomography or high energy physics.