Enhancing photoluminescence in perovskite nanostructures with metal nanoparticles and nanocavities

Thesis

Enhancing photoluminescence (PL) is central to advancing optoelectronic and quantum photonic technologies. Low-dimensional CsPbX3 perovskite nanomaterials have emerged as outstanding emitters due to their large exciton binding energies, high oscillator strength, and the ability to sustain excitons at room temperature. Strategies such as cavity-induced Purcell enhancement and plasmonic local-field amplification offer powerful means to modulate their optical response, markedly boosting PL intensity. This thesis investigates the coupling between metal nanoparticles (NPs), optical nanocavities, and lead-halide perovskite nanostructures to actively control and enhance emission, establishing both mechanisms and design principles for hybrid light–matter architectures.

Pronounced plasmon-enhanced emission was demonstrated in Ag/CsPbBr3 nanowire hybrids. A two-step process combining superfluid helium droplet deposition with wet-chemical growth enables precise NP sizing and tunable plasmon resonances, while minimizing damping from chemical residues. Within a tailored four-layer geometry, this approach yields an 8.5-fold PL intensity increase at 4 K, with time-resolved measurements confirming accelerated recombination from plasmon– exciton coupling.

Magnesium is further introduced as an alternative plasmonic material to conventional noble metals. Benefiting from earth abundance and low cost, Mg supports competitive plasmonic resonances and is readily synthesized via colloidal routes into spheroidal Mg/MgO core–shell NPs. Near-field coupling between their dipolar modes and CsPbBr3 nanowire emission delivers PL enhancement factors of 1.7× and 4.1× for different sub-100 nm particles at room temperature. Although weaker than Ag in analogous designs, Mg’s self-limiting oxide shell provides improved ambient stability, highlighting a sustainable pathway for plasmonic integration.

Finally, micro-PL studies on CsPbI3 nanoplatelets reveal pronounced quantum confinement, with excitonic energies and recombination dynamics tuned by thickness. Cavity-assisted measurements show brighter and more symmetric emission spectra relative to off-cavity references, though without significant lifetime shortening. These results indicate that excitation/collection efficiency and spectral filtering dominate the observed enhancements, while Purcell acceleration remains weak under the current cavity design.

Collectively, this work establishes new routes to control and amplify light emission in perovskite nanostructures through plasmonic and cavity coupling, providing insights for the rational design of scalable hybrid architectures for optoelectronics and quantum photonics.

Authors: Wang, Q

• DOI: 10.5287/ora-g7mbazgqz
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English