Plasmon‐Assisted Directional Infrared Photoluminescence of HgTe Nanocrystals

Abstract

HgTe nanocrystals offer a unique spectral tunability with both absorption and emission covering the near and mid‐infrared as well as the THz window. Nevertheless, a very limited amount of work is dedicated to electroluminescence from this material. An efficient diode not only requires designing a structure that achieves a high electrical efficiency (i.e., efficient electron and hole injections), but also finding a way to efficiently extract the emitted photons. The shift from visible to infrared certainly demands revisiting the strategies proposed for shorter wavelengths (microlens arrays). Here, a metallic grating is used to enhance the photoluminscence signal up to a factor of 4 while enabling directionality in the emission, which is driven by the grating period.

Uncooled High Detectivity Mid-Infrared Photoconductor Using HgTe Quantum Dots and Nanoantennas

“…Enhanced PL has been previously observed with PbS CQDs directly deposited on square metal antenna arrays . This is in contrast to the common observation of quenching on metal surfaces . Here, we still observe enhanced PL even with very thin films of HgTe CQDs (∼25 nm) (Figure S11).…”

Observation of Quasi-Invariant Photocarrier Lifetimes in PbS Nanocrystal Assemblies Coupled to Resonant and Nonresonant Arrays of Optical Antennas

“…In this respect, we note that compact layers of CdSe-CdS/ZnS core–shell NCs were recently shown to obey the local Kirchhoff law in the steady-state, raising the prospect that they follow transient dynamics similar to those evidenced here. On the other hand, experiments on HgTe NC assemblies have shown that their PL is quenched when placed in direct contact with metallic structures, which is the opposite behavior of the PbS NCs investigated in the present study and elsewhere. ,− It would also be interesting to extend the study to systems in which FRET among emitters is even more pronounced, such as stacks of CdSe nanoplatelets in which the FRET interaction times reach the picosecond scale, allowing photocarrier migration over hundreds of nm from their excitation point …”

2D Silver-Nanoplatelets Metasurface for Bright Directional Photoluminescence, Designed with the Local Kirchhoff’s Law

“…The same approach could be used to design photoluminescent metasurfaces controlling the emitted polarization as reported recently in the context of thermal emission . The method could also be applied to optimize dielectric photoluminescent metasurfaces, ,, which could enable sources with narrower emission cones, as well as electroluminescent metasurfaces. ,, …”

“…30 The method could also be applied to optimize dielectric photoluminescent metasurfaces, 23,60,61 which could enable sources with narrower emission cones, as well as electroluminescent metasurfaces. 16,17,62…”

“…It is possible to overcome this issue by generating spatial coherence. Directional emission based on emitters deposited on a plasmonic or dielectric grating has been achieved with dye molecules, − fluorescent glass, quantum wells, − and more recently semiconductor nanocrystals. − In all these references, − restoration of a spatially coherent field was done by coupling efficiently any emitter to a delocalized mode such as a surface plasmon, a surface phonon polariton, or a guided wave. A metasurface consisting of resonators can also be used if they interact so that surface lattice resonance modes exist .…”