CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
Nanoscale. 2019 Feb 14;11(7):3145-3153. doi: 10.1039/c8nr09634a.
Recently, the light-matter interaction of perovskite microcavities has been widely explored for its great potential in low-threshold lasing devices. However, the mechanism of perovskite lasing remains unclear to date. In this study, we demonstrated high-quality single-mode excitonic lasing in CsPbBr3 microspheres, providing an ideal platform to study the underlying physics of lasing behavior. We show that the lasing mechanism shifts from the exciton-exciton scattering to the exciton-phonon scattering with the increase in temperature from 77 to 300 K, which was verified by temperature-dependent photoluminescence (PL), time-resolved photoluminescence (TRPL) as well as temperature-dependent Raman spectroscopy. Furthermore, by analyzing PL line width broadening with varied temperatures, we found that two different phonon modes were involved in the exciton-phonon scattering process. The scattering from the low-energy phonon (∼8.6 meV) is the dominant source of exciton-phonon coupling in the intermediate temperature range (77 to 230 K), while the high-energy phonon (∼15.3 meV) dominates from 230 K to room temperature. These results confirm the lasing mechanism in such perovskite-based micro/nano-cavities and significantly influence the development of future low-threshold lasers.
最近，钙钛矿微腔中的光物质相互作用因其在低阈值激光器件中的巨大潜力而得到了广泛的探索。然而，到目前为止，钙钛矿激光的机制仍不清楚。在这项研究中，我们在 CsPbBr3 微球中演示了高质量的单模激子激光，为研究激光行为的基础物理提供了理想的平台。我们表明，随着温度从 77 K 升高到 300 K，激光机制从激子-激子散射转变为激子-声子散射，这通过温度依赖的光致发光（PL）、时间分辨光致发光（TRPL）以及温度依赖的拉曼光谱得到了验证。此外，通过分析不同温度下 PL 线宽展宽，我们发现两个不同的声子模式参与了激子-声子散射过程。在中间温度范围（77 至 230 K）中，低能声子（约 8.6 meV）的散射是激子-声子耦合的主要来源，而在 230 K 至室温范围内，高能声子（约 15.3 meV）占主导地位。这些结果证实了这种基于钙钛矿的微/纳腔中的激光机制，并对未来低阈值激光器的发展产生了重大影响。
