Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, China.
Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei Key Laboratory of Ferro and Piezoelectric Materials and Devices, Faculty of Physics and Electronic Science, Hubei University, Wuhan, 430062, China.
Adv Mater. 2018 Aug;30(31):e1801805. doi: 10.1002/adma.201801805. Epub 2018 Jun 19.
1D nanowires of all-inorganic lead halide perovskites represent a good architecture for the development of polarization-sensitive optoelectronic devices due to their high absorption efficient, emission yield, and dielectric constants. However, among as-fabricated perovskite nanowires with the lateral dimensions of hundreds nanometers so far, the optical anisotropy is hindered and rarely explored owing to the invalidating of electrostatic dielectric mismatch in the physical dimensions. Here, well-aligned CsPbBr and CsPbCl nanowires with thickness T down to 15 and 7 nm, respectively, are synthesized using a vapor phase van der Waals epitaxial method. Strong emission anisotropy with polarization ratio up to ≈0.78 is demonstrated in the nanowires with T < 40 nm due to the electrostatic dielectric confinement. With the increasing of thickness, the polarization ratio remarkably reduces monotonously to ≈0.17 until T ≈140 nm; and further oscillates in a small amplitude owing to the wave characteristic of light. These findings not only represent a demonstration of perovskite-based polarization-sensitive light sources, but also advance fundamental understanding of their polarization properties of perovskite nanowires.
1D 纳米线全无机卤化铅钙钛矿由于其高吸收效率、发光产率和介电常数，代表了一种发展极化敏感光电设备的良好结构。然而，在迄今为止具有数百纳米横向尺寸的制造钙钛矿纳米线中，由于物理尺寸中静电介电失配的失效，光学各向异性受到阻碍，很少被探索。在这里，使用气相范德华外延方法合成了厚度 T 分别降至 15nm 和 7nm 的取向良好的 CsPbBr 和 CsPbCl 纳米线。在 T < 40nm 的纳米线中，由于静电介电限制，表现出高达 ≈0.78 的强发射各向异性比。随着厚度的增加，偏振比单调地显著降低到 ≈0.17，直到 T ≈140nm；并由于光的波动特性而以小幅度振荡。这些发现不仅代表了基于钙钛矿的极化敏感光源的演示，而且也推进了对钙钛矿纳米线极化性质的基本理解。
