Lead halide perovskites are promising materials for various optoelectronic device applications such as solar cells, light-emitting diodes, and lasers. Three-dimensional perovskites, for example, CH₃NH₃PbI₃ and CsPbBr₃, have been demonstrated to be high-gain active media for low-threshold lasing. In contrast, layered perovskites, for example, (CH₃(CH₂)₃NH₃)₂PbI₄, are known to be difficult to show lasing oscillation especially at room temperature, despite their robustness for the environment. Here we reveal the bottleneck for the lasing oscillation in layered perovskites through systematic experiments on time-resolved photoluminescence and transient absorption. It is found that the energy transfer to a long-lived exciton state with triplet nature is enhanced by increasing pumping fluence or by introducing a high-Q microcavity, hindering the formation of population inversion. These results are consistent with a coupled rate-equation model as well as previous works and paves the way for designing low threshold layered perovskite lasers.

中文翻译：

---

层状卤化钙钛矿型晶体平板和微腔中的激发动力学

卤化钙钛矿是用于各种光电器件应用的有前途的材料，例如太阳能电池，发光二极管和激光器。三维钙钛矿，例如，CH ₃ NH ₃碘化铅₃和CsPbBr ₃，已被证明是低阈值激射高增益活性介质。相反，层状钙钛矿例如为（CH ₃（CH ₂）₃ NH ₃）₂ PbI ₄众所周知，尽管它们具有对环境的鲁棒性，但是它们尤其在室温下难以显示出激光振荡。在这里，我们通过时间分辨的光致发光和瞬态吸收的系统实验揭示了层状钙钛矿中激光振荡的瓶颈。已发现，通过增加泵浦注量或通过引入高Q微腔，可阻碍向三重态的长寿命激子态的能量转移，从而阻碍了人口反转的形成。这些结果与耦合速率方程模型以及先前的工作一致，为设计低阈值分层钙钛矿激光器铺平了道路。