Low-threshold cavity-enhanced superfluorescence in polyhedral quantum dot superparticles.

Due to the unique and excellent optical performance and promising prospect for various photonics applications, cavity-enhanced superfluorescence (CESF) in perovskite quantum dot assembled superstructures has garnered wide attention. However, the stringent requirements and high threshold for achieving CESF limit its further development and application. The high threshold of CESF in quantum dot superstructures is mainly attributed to the low radiation recombination rate of the quantum dot and the unsatisfactory light field limiting the ability of the assembled superstructures originating from low controllability of self-assembly. Herein, we propose a strategy to reduce the threshold of CESF in quantum dot superstructure microcavities from two aspects: facet engineering optimization of quantum dot blocks and controllability improvement of the assembly method. We introduce dodecahedral quantum dots with lower nonradiative recombination, substituting frequently used cubic quantum dots as assembly blocks. Besides, we adopt the micro-emulsion droplet assembly method to obtain spherical perovskite quantum dot superparticles with high packing factors and orderly internal arrangements, which are more controllable and efficient than the conventional solvent-drying methods. Based on the dodecahedral quantum dot superparticles, we realized low-threshold CESF (Pth = 15.6 μJ cm). Our work provides a practical and scalable avenue for realizing low threshold CESF in quantum dot assembled superstructure systems.