Hyperbolic metamaterial (HMM), a sub-wavelength periodic artificial structure with hyperbolic dispersion, can enhance the spontaneous emission of quantum emitters. Here, we demonstrate the large spontaneous emission rate enhancement of an organic dye placed in a grating coupled hyperbolic metamaterial (GCHMM). A two-dimensional (2D) silver diffraction grating coupled with an Ag/Al₂O₃ HMM shows 18-fold spontaneous emission decay rate enhancement of dye molecules with respect to the same HMM without grating. The experimental results are compared with analytical models and numerical simulations, which confirm that the observed enhancement of GCHMM is due to the outcoupling of non-radiative plasmonic modes as well as strong plasmon-exciton coupling in HMM via diffracting grating.

Vanadium pentoxide (V₂O₅) thin films were grown on indium tin oxide-coated flexible Kapton substrates by home-built activated reactive evaporation technique. Film depositions were carried out at optimised oxygen partial pressure of 1 × 10⁻³ Torr and plasma power of 8 W, and we investigated their microstructural and opto-electrochromic properties as a function of substrate temperature. The V₂O₅ films grown at T_s = 473 K exhibited a nano-crystalline nature as evidenced from X-ray diffraction, atomic force microscopy and Raman studies. The nano-crystalline films composed of vertical elliptical-shaped grainy morphology demonstrated a high optical transmittance of 75% with an estimated optical bandgap of 2.38 eV. The dry lithiated nano-crystalline V₂O₅ films demonstrated an optical modulation of 36.1% with a coloration efficiency value of 26.2 cm²/C at a wavelength of 550 nm. As-deposited nano-crystalline V₂O₅ thin films demonstrated a constant discharge capacity of about 60 μAh cm⁻² μm⁻¹ for a few cycles at room temperature in the potential window of 4.0 to 2.5 V.

Improved properties of LiBOB-based solid polymer electrolyte