Enhanced Spontaneous Emission Rate and Luminescence Intensity of CsPbBr3 Quantum Dots Using a High-Q Microdisk Cavity

Perovskite quantum dots (QDs) are high-efficiency optoelectronic materials attracting great interest, but further improvement in the luminescence efficiency is crucial for their application. In this work, we enhance both the spontaneous emission rate and the photoluminescence (PL) intensity of CsPbBr3 QDs by coupling them to a high quality (Q) factor SiO2 microdisk cavity. Compared to conventional metal plasmonic cavities, the dielectric cavity structure suppresses the effects of quenching and energy transfer, which could introduce complex fluctuations and nonradiative decays. As such, we obtain a 5.9-fold enhancement of the PL intensity and a 5.6-fold enhancement of the emission rate. Moreover, the different enhancement behaviors for phonon sidebands allow us to further explore the different components in the broad emission peak of ensembled QDs. These results demonstrate the great potential of microdisk cavities in enhancing the luminescence in optoelectronic devices and exploring the exciton-photophysics of perovskite QDs.

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.

Strong Purcell enhancement at telecom wavelengths afforded by spinel Fe3O4 nanocrystals with size-tunable plasmonic properties

Developments in the field of nanoplasmonics have the potential to advance applications from information processing and telecommunications to light-based sensing. Traditionally, nanoscale noble metals such as gold and silver have been used to achieve the targeted enhancements in light-matter interactions that result from the presence of localized surface plasmons (LSPs). However, interest has recently shifted to intrinsically doped semiconductor nanocrystals (NCs) for their ability to display LSP resonances (LSPRs) over a much broader spectral range, including the infrared (IR). Among semiconducting plasmonic NCs, spinel metal oxides (sp-MOs) are an emerging class of materials with distinct advantages in accessing the telecommunications bands in the IR and affording useful environmental stability. Here, we report the plasmonic properties of Fe₃O₄ sp-MO NCs, known previously only for their magnetic functionality, and demonstrate their ability to modify the light-emission properties of telecom-emitting quantum dots (QDs). We establish the synthetic conditions for tuning sp-MO NC size, composition and doping characteristics, resulting in unprecedented tunability of electronic behavior and plasmonic response over 450 nm. In particular, with diameter-dependent variations in free-electron concentration across the Fe₃O₄ NC series, we introduce a strong NC size dependency onto the optical response. In addition, our observation of plasmonics-enhanced decay rates from telecom-emitting QDs reveals Purcell enhancement factors for simple plasmonic-spacer-emitter sandwich structures up to 51-fold, which are comparable to values achieved previously only for emitters in the visible range coupled with conventional noble metal NCs.

Plasmonic-perovskite solar cells, light emitters, and sensors

The field of plasmonics explores the interaction between light and metallic micro/nanostructures and films. The collective oscillation of free electrons on metallic surfaces enables subwavelength optical confinement and enhanced light-matter interactions. In optoelectronics, perovskite materials are particularly attractive due to their excellent absorption, emission, and carrier transport properties, which lead to the improved performance of solar cells, light-emitting diodes (LEDs), lasers, photodetectors, and sensors. When perovskite materials are coupled with plasmonic structures, the device performance significantly improves owing to strong near-field and far-field optical enhancements, as well as the plasmoelectric effect. Here, we review recent theoretical and experimental works on plasmonic perovskite solar cells, light emitters, and sensors. The underlying physical mechanisms, design routes, device performances, and optimization strategies are summarized. This review also lays out challenges and future directions for the plasmonic perovskite research field toward next-generation optoelectronic technologies.