Over a thousand-fold enhancement of the spontaneous emission rate for stable core-shell perovskite quantum dots through coupling with novel plasmonic nanogaps

High Purcell enhancement structures and stable emitters are essential prerequisites for the successful development of novel fast-operating active devices. Furthermore, a uniform enhancement of the spontaneous emission rate is critical for practical applications. Despite considerable efforts being made to meet these requirements, achieving them still remains a challenging task. In this work, we demonstrate that placing stable core-shell perovskite quantum dots (PQDs) in the nanogap region of hole/sphere-based nanogap structures (HSNGs) can enhance the spontaneous emission rate by more than a thousand-fold (up to a factor of ∼1080) compared to PQDs in solution. This enhancement factor is the highest value reported using PQDs, exceeding previously reported values by two orders of magnitude. Notably, the enhancement factor of the emission rate in the HSNG maintains large values across the samples, with values ranging from ∼690 to ∼1080. Furthermore, the structural stabilities of the PQDs are remarkably enhanced with the incorporation of SiO₂ shells, which is validated by monitoring the changes in photoluminescence intensities over time during continuous laser exposure. As a result, the HSNG with stable core-shell PQDs offers great potential for fast optical device applications that require high performance and long-term operational stability.