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

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 (H(2)MDAP)BiI5 (1, H(2)MDAP = 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 x 7 x 4 mm(3) 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 x 10(11)cm(-3), carrier mobility of 1.42 cm(2)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 , similar to 1.0 mu C Gy(air)(-1) cm(-2). These results throw light on further exploration on X-ray-sensitive materials based on the lead-free metal halogen hybrids.