摘要
The structure of a new oxygen-rich bismuth oxyselenide, Bi 14 O 24 Se, is resolved. • Bi 14 O 24 Se combines a wide 2.47 eV band gap with unexpectedly strong broadband nonlinear absorption. • Bi 14 O 24 Se enables ultrafast pulses and narrow-linewidth coherent lasing. Bi 2 O 2 Se is a representative bismuth oxyselenide for optoelectronic and photonic applications, but its narrow bandgap and free-carrier background limit stable optical modulation. While defect engineering, doping, and heterostructure construction can improve local properties, they remain constrained by the intrinsic Bi 2 O 2 Se framework. Exploring new Bi-O-Se phases therefore offers a route to reconstruct the crystal framework and band-edge electronic structure. Here, by adjusting the Bi 2 O 3 /Bi 2 Se 3 precursor ratio and conducting the solid-state reaction under a flowing O 2 /Ar atmosphere, we steer the Bi-O-Se system toward an oxygen-rich composition region and identify Bi 14 O 24 Se as a structurally defined oxygen-rich bismuth oxyselenide phase. Electronic-structure calculations reveal a wide bandgap and strong oxygen-state participation at the band edges. Electron localization function analysis further distinguishes the local bonding characteristics, revealing appreciable bond-centered electron localization along the Se O linkages and a more strongly polarized electron distribution across the Bi O interactions. Experimentally, Bi 14 O 24 Se exhibits a distinct optical absorption edge, good thermal stability, and pronounced near-infrared saturable absorption, with modulation depths of 18.3% and 13.5% at 1 and 1.5 μm, respectively, as well as low saturation intensities of 0.52 and 0.16 kW/cm 2 . These results establish Bi 14 O 24 Se as a structurally defined oxygen-rich bismuth oxyselenide and provide a new material basis for understanding how oxygen-rich frameworks reshape the structure-electronic-optical relationship in Bi-O-Se phases. Download: Download high-res image (186KB) Download: Download full-size image
危险品化学品经营许可证（带存储）