Composition-Graded Cesium Lead Halide Perovskite Nanowires with Tunable Dual-Color Lasing Performance.

Huang, Ling; Gao, Qinggang; Sun, Ling-Dong; Dong, Hao; Shi, Shuo; Cai, Tong; Liao, Qing; Yan, Chun-Hua · Adv Mater · 2018

basic_science · Level V

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Abstract

Cesium lead halide (CsPbX<sub>3</sub> ) perovskite has emerged as a promising low-threshold multicolor laser material; however, realizing wavelength-tunable lasing output from a single CsPbX<sub>3</sub> nanostructure is still constrained by integrating different composition. Here, the direct synthesis of composition-graded CsPbBr<sub>x</sub> I<sub>3-</sub><sub>x</sub> nanowires (NWs) is reported through vapor-phase epitaxial growth on mica. The graded composition along the NW, with an increased Br/I from the center to the ends, comes from desynchronized deposition of cesium lead halides and temperature-controlled anion-exchange reaction. The graded composition results in varied bandgaps along the NW, which induce a blueshifted emission from the center to the ends. As an efficient gain media, the nanowire exerts position-dependent lasing performance, with a different color at the ends and center respectively above the threshold. Meanwhile, dual-color lasing with a wavelength separation of 35 nm is activated simultaneously at a site with an intermediate composition. This position-dependent dual-color lasing from a single nanowire makes these metal halide perovskites promising for applications in nanoscale optical devices.