Plasmon Enhanced Light Emission in Metal Halide Perovskite Nanowires

Photonic nanowires based on semiconductor materials have potential applications in light generation, propagation, detection, and amplification at the nanoscale and play a key role in the development of integrated photonic/electronic devices. To achieve the best optical performance for these applications it is crucial to enhance the photon conversion efficiency of the nanowires. A promising way to enhance light emission from nanowires is to combine semiconductors with noble metals. The strong confinement of electromagnetic field resulting from plasmonic structures can effectively transfer surface plasmon resonance energy to semiconductors via excited electrons and thus effectively enhance the photoluminescence (PL) yield. However, the synthesis of hybrid metal-semiconductor nanowires having desirable optical properties has proven challenging due to the non-wetting between the two types of materials.<br/><br/>Here we report plasmon-enhanced light emission from a hybrid nanowire consisting of noble metal and semiconductor materials. The demonstration is performed in a cesium lead halide perovskite-based four-layer structure (CsPbBr3/PMMA/Ag/Si) designed to limit plasmonic losses in the metal while exhibiting efficient surface plasmon-photon coupling at moderate power. We used solution processing to make the nanowires, which were then spin-coated onto a Si substrate coated with Ag nanoparticles. These were produced by using quantized vortices in superfluid helium, which circumvents the non-wetting between the two types of materials. We employ temperature-dependent micro-photoluminescence spectroscopy (from 4 K to 300 K), to study the optical properties of the nanowires. We excite the individual nanowires by considering several configurations with Ag nanoparticle diameters ranging from 7 to 10 nm and PMMA layer thicknesses ranging from 5 to 25 nm to better understand the optical performance. The study, conducted with 100 fs laser pulses at a repetition rate of 76 MHz and at an excitation wavelength of 400 nm reveals that a 5 nm thick PMMA layer and 7.5 nm sized Ag nanoparticles enhanced the PL intensity by approx. 40% compared to pure semiconductor structures at 4 K. In addition, we investigate the emission dynamics of carriers and excitons in the nanowires using time-resolved photoluminescence spectroscopy techniques. Observation shows enhanced carrier recombination dynamics due to plasmonic interactions with the perovskite. These results show a potential way to excite hybrid nanowires at sufficiently low photon density so that single photon excitation/emission could be possible from these structures. Moreover, this fundamental demonstration confirms a proof-of-concept for further work involving plasmon-enhanced light emission from core-shell metal/semiconductor nanowires and opens the door for realizing lead halide perovskite-based micro and nanolasers in the visible range and more broadly for developing on-chip nanophotonic devices.