Feng Bin, Zhao Shixuan, Razdolski Ilya, Liu Feihong, Peng Zhiwei, Wang Yaorong, Zhang Zhedong, Ni Zhenhua, Xu Jianbin, Lei Dangyuan
Department of Materials Science and Engineering, Centre for Functional Photonics, and Hong Kong Branch of National Precious Metals Material Engineering Research Centre, City University of Hong Kong, Hong Kong S.A.R., 999077, China.
Department of Physics, City University of Hong Kong, Hong Kong S.A.R., 999077, China.
Nano Lett. 2025 Jan 29;25(4):1609-1616. doi: 10.1021/acs.nanolett.4c05647. Epub 2025 Jan 8.
The emission efficiency of interlayer excitons (IEs) in twisted 2D heterostructures has long suffered from momentum mismatch, limiting their applications in ultracompact excitonic devices. Here, we report strong room-temperature emission of the momentum-forbidden IEs in a 30°-twisted MoS/WS heterobilayer. Utilizing the Purcell effect of a compact plasmonic nanocavity boosts the IE emission intensity in the cavity by over 2 orders of magnitude. We further study the interplay of this Purcell enhancement and phonon assistance in 30°- and 0°-twisted heterostructures. Temperature-dependent and time-resolved spectroscopic measurements reveal that the IE enhancement in the 30°-twisted case involves competition between IE and intralayer-exciton emissions, which is remarkably distinct from the 0°-twisted case. We propose an exciton decay model capturing the features of phonon-assisted momentum compensation and Purcell enhancement in the IE emission, showing consistency with the experimental measurements. Our results enrich the understanding of the nanocavity-assisted light-matter interaction for momentum-indirect excitonic transitions.
长期以来，扭曲二维异质结构中层间激子（IEs）的发射效率一直受到动量失配的影响，这限制了它们在超紧凑型激子器件中的应用。在此，我们报道了在30°扭曲的MoS/WS异质双层中动量禁戒的层间激子在室温下的强发射。利用紧凑型等离子体纳米腔的珀塞尔效应，可将腔内的层间激子发射强度提高两个数量级以上。我们进一步研究了这种珀塞尔增强与30°和0°扭曲异质结构中声子辅助之间的相互作用。温度依赖和时间分辨光谱测量表明，30°扭曲情况下的层间激子增强涉及层间激子与层内激子发射之间的竞争，这与0°扭曲情况明显不同。我们提出了一个激子衰变模型，该模型捕捉了层间激子发射中声子辅助动量补偿和珀塞尔增强的特征，与实验测量结果一致。我们的结果丰富了对纳米腔辅助的动量间接激子跃迁的光-物质相互作用的理解。
