Abstract
Chemically synthesized near-infrared to mid-infrared (IR) colloidal quantum dots (QDs) offer a promising platform for the realization of devices including emitters, detectors, security, and sensor systems. However, at longer wavelengths, the quantum yield of such QDs decreases as the radiative emission rate drops following Fermi’s golden rule, while non-radiative recombination channels compete with light emission. Control over the radiative and non-radiative channels of the IR-emitting QDs is crucially important to improve the performance of IR-range devices. Here, we demonstrate strong enhancement of the spontaneous emission rate of near- to mid-IR HgTe QDs coupled to periodically arranged plasmonic nanoantennas, in the form of nanobumps, produced on the surface of glass-supported Au films via ablation-free direct femtosecond laser printing. The enhancement is achieved by simultaneous radiative coupling of the emission that spectrally matches the first-order lattice resonance of the arrays, as well as more efficient photoluminescence excitation provided by coupling of the pump radiation to the local surface plasmon resonances of the isolated nanoantennas. Moreover, coupling of the HgTe QDs to the lattice plasmons reduces the influence of non-radiative decay losses mediated by the formation of polarons formed between QD surface-trapped carriers and the IR absorption bands of dodecanethiol used as a ligand on the QDs, allowing us to improve the shape of the emission spectrum through a reduction in the spectral dip related to this ligand coupling. Considering the ease of the chemical synthesis and processing of the HgTe QDs combined with the scalability of the direct laser fabrication of nanoantennas with tailored plasmonic responses, our results provide an important step towards the design of IR-range devices for various applications.
Highlights
Inexpensive near-infrared (IR) to mid-IR sources and detectors operating at room temperature are expected to revolutionize current technologies for the realization of various night vision and security systems, sensing and spectroscopy tools, etc
We demonstrate an efficient tuning of the spontaneous emission of near- to mid-IR-emitting HgTe quantum dots (QDs) placed above a high-quality plasmonic nanobump array produced on the surface of glass-supported Au films via inexpensive ablation-free direct femtosecond laser patterning
Plasmonic arrays composed of ordered nanobumps were fabricated via direct fs-laser patterning of a 50-nm thick glass-supported Au film (Fig. 1b) according to the procedure described in the Materials and methods section
Summary
Inexpensive near-infrared (IR) to mid-IR sources and detectors operating at room temperature are expected to revolutionize current technologies for the realization of various night vision and security systems, sensing and spectroscopy tools, etc. The emission properties of any quantum emitter are known to be strongly modified in the vicinity of a plasmonic nanostructure, which can resonantly interact with pump radiation via excitation of collective oscillations of a free electron plasma[4]. Both spontaneous radiative and non-radiative emission rates, the lifetime of an Sergeev et al Light: Science & Applications (2020)9:16 excited state, the directionality and the emission spectrum can be significantly tailored[5,6,7,8,9,10,11], as predicted in the pioneering work of Purcell[12]. Real-life applications will require millions of high-quality plasmonic nanoantennas arranged into well-ordered arrays, which makes their fabrication with existing lithographic techniques time-consuming and cost-consuming
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