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A Lead-Free Hybrid Iodide with Quantitative Response to X‑ray Radiation

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posted on 2019-07-31, 12:08 authored by Kewen Tao, Yaobin Li, Chengmin Ji, Xitao Liu, Zhenyue Wu, Shiguo Han, Zhihua Sun, Junhua Luo
Single crystals of lead halide hybrid perovskites (e. g., CH3NH3PbI3 and CsPbBr3) have been developed as promising candidates for X-ray detection, owing to their excellent attributes including low trap density, high X-ray absorption cross section, and high carrier mobility. The toxicity of lead, however, is a potential bottleneck that hinders their device application toward green and sustainable competitors. Herein, we reported a new lead-free bismuth-iodide hybrid of (H2MDAP)­BiI5 (1, H2MDAP = N-methyl-1,3-diaminopropanium), adopting one-dimensional (1D) metal-halogen frameworks, which behaves as a potential alternative for X-ray detection. Large-size single crystals of 1 with sizes up to 9 × 7 × 4 mm3 were successfully grown via top-seeded solution growth method. The as-grown crystal exhibits notable semiconducting properties, including a narrow bandgap of 1.83 eV, trap density of 3.6 × 1011 cm–3, carrier mobility of 1.42 cm2 V–1 s–1, and high X-ray absorption coefficient. Consequently, the fabricated crystal-based X-ray photoconductor enables the conversion of X-ray to electrical signals with a sensitivity of ∼1.0 μC Gyair–1 cm–2. These results throw light on further exploration on X-ray-sensitive materials based on the lead-free metal halogen hybrids.

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