Organic Monolithic Natural Hyperbolic Material

Abstract

Materials with hyperbolic dispersion are the key to a variety of photonic applications involving nanoimaging, hyper-lensing, and spontaneous emission engineering, due to the availability of high k modes. Here we demonstrate that spin-coated polycrystalline organic semiconducting films with a layered molecular packing structure can exhibit a hyperbolic dispersion over a wide spectral range and support the presence of surface excitonic polaritons. This was evidenced from 670 to 920 nm and is related to the negative real part of the dielectric permittivity of the selected quinoidal organic semiconductor. In addition, the accessible high k modes lead to changes in the spontaneous emission decay rate and photoluminescence quantum yield of emitters placed nearby the organic monolithic (composed of only one molecule and not necessitating an alternating multilayer structure) natural hyperbolic material. This study opens a new route toward single-step solution manufacturing of large-area, low-cost, and flexible organic photonic metadevices with hyperbolic dispersion.

Metamaterial assisted illumination nanoscopy via random super-resolution speckles

“…1a. The ideal HMM has an unlimited k-space, while a practical HMM, made by Ag-SiO 2 multilayer, has a k-space limitation from its periodicity [23][24][25][26] . A multilayer with a smaller period of alternating layers supports a higher spatial frequency.…”

Unprecedented Fluorophore Photostability Enabled by Low‐Loss Organic Hyperbolic Materials

“…Herein, we demonstrate an unprecedented fluorophore photostability enabled by a self‐assembled organic hyperbolic material (OHM) film [ 28 ] in the visible spectrum. Compared to traditional HMMs [ 22,29,30 ] made of noble metal structures and other natural hyperbolic materials, [ 31–33 ] the OHMs used in this work feature a Lorentz‐type dispersion [ 33,34 ] with low‐loss natural hyperbolic polariton modes, [ 28 ] and thus support an extremely large LDOS and a large Purcell factor. [ 35 ] Moreover, this low‐loss hyperbolic nature of the OHM films also makes an efficient fluorescence enhancement without any outcoupling structure possible.…”

“…For Ag, the resonance peak wavelength is centered around 440 nm, [ 39 ] and for Au it is centered at 620 nm. [ 40–42 ] TiN‐based HMMs, [ 43,44 ] Ag‐based HMMs, [ 20,21,23,33,45–50 ] and Au‐based HMMs [ 40,51,52 ] support a broadband but relatively small PF. The OHMs used in this work provide PFs two orders of magnitude larger than the values found in those plasmonic materials, and even comparable to the values attained by using plasmonic nanostructures such as nanoantennae, [ 11,41 ] nanocavities, [ 53 ] and nanogratings [ 21,48 ] in the spectral range of 480–560 nm.…”

Low‐Loss Organic Hyperbolic Materials in the Visible Spectral Range: A Joint Experimental and First‐Principles Study

“…An important challenge which must be overcome to fully exploit the useful properties of naturally hyperbolic media is the development of low-loss, practical hyperbolic materials at visible frequencies. Recent studies of organic films made by the solution-processing method have shown strong Lorentz-type optical dispersions including a negative real part of permittivity from molecular conformation and strong inter-molecular interactions [30][31][32] . In the case that a transition's oscillator strength is sufficiently large, the maximal Im(ε) 1, Re(ε) can become negative.…”

“…In the case that a transition's oscillator strength is sufficiently large, the maximal Im(ε) 1, Re(ε) can become negative. Since Im(ε) decays faster than Re(ε), as frequency is tuned away from resonance, there can exist an off-resonance frequency range over which Re(ε) is negative and Im(ε) is small [30][31][32] . Thus, organic films exhibiting these specific optical properties are likely to be attractive substitutes for metals at visible frequencies.…”