Single-Step Synthesis of Cs <sub>3</sub> Bi <sub>2</sub> I <sub>9</sub> Nanocrystals for Scalable Direct X-ray Detectors
Ramavath Babu, Joydip Ghosh, Nadine J. Schrenker, Kavya Reddy Dudipala, Yi‐Teng Huang, Yixin Wang, Shiling Dong, Deepika Gaur, Sara Bals, Sergio Gómez‐Graña, Xian Wei Chua, Isabel Braddock, Matthew C. Veale, Michael Wilson, Jack M. Woolley, Akshay Rao, Robert L. Z. Hoye, Lakshminarayana Polavarapu
Abstract
High Resolution Image Download MS PowerPoint Slide Lead-free perovskite-inspired materials have emerged as promising candidates for direct X-ray detection. However, in the early exploration of emerging materials, the focus was on large single crystals. Herein, we report a facile, scalable, single-step synthesis of high-quality Cs 3 Bi 2 I 9 nanocrystals (NCs) directly from their precursor powders through an ultrasonication approach. The large-scale synthesis of the NCs allowed for the production of 0.78 cm 2 pellets used in the fabrication of X-ray detection devices, which exhibit a high bulk resistivity of 1 × 10 11 Ω cm and a low dark current density of 3.3 nA cm –2 under an applied bias of 50 V (357 V cm –1 electric field). These devices achieve a limit detection of 108 nGy air s –1, an order of magnitude improvement over the a-Se used in commercial medical imaging, along with stable current under continuous X-ray exposure with a peak energy of 35 keV p . Finally, we demonstrate the scale-up of these detectors by producing thick films 9 cm 2 in area, achieving a performance comparable to that of the detectors based on pellets.