Enhanced photoluminescence and directional white-light generation by plasmonic array

Abstract

White light-emitting diodes (LEDs), light sources that combine blue LEDs and yellow phosphors, are equipped with bulky optics such as lenses, mirrors, and/or reflectors to shape the light into the required directions. The presence of bulky optics causes optical loss and limits the design. Here, a periodic array of metallic nanocylinders, which exhibits a high scattering efficiency owing to the excitation of localized surface plasmon resonance, is proposed as an alternative means of achieving a directional output without the limitations of bulky optics. A prototype of a directional light emitter is fabricated consisting of an Al nanocylinder array on a yellow phosphor plate and a blue laser. The array shapes the yellow luminescence into the forward direction and generates directional quasi-white light (correlated color temperature of 4900 K). The intensity enhancement reaches a factor of five in the forward direction and is further improved up to a factor of seven by the deposition of a multilayer dichroic mirror on the back side of the phosphor plate, resulting in conversion efficiencies as high as 90 lm/W. Our results pave the way toward the development of efficient and compact directional white-light-source devices without any bulky optics.

Influence on structural, electronic and optical properties of Fe doped ZnS quantum dot: A density functional theory based study

“…Since PL intensity is directly proportional to the absorption coefficient () according to equation [77] where I is the PL intensity, C is the out coupling and is the quantum yield, the normalized value PL intensity is similar as the normalized value of which also related to Terahertz Elliott formula [78]. Hence, to know more clearly the luminescence properties for both the doped and undoped ZnS the normalized PL intensity curve has been illustrated into the Figure 9 as a function of wavelength obtained from the value of .…”

Directional emission of white light via selective amplification of photon recycling and Bayesian optimization of multi-layer thin films

“…On the nanoscale, meta- 18 – 20 and microlenses 21 , 22 have been introduced to manipulate light by microscopic structures. In addition, scientific work has been conducted towards the development of incoherent and directional light sources based on periodic or random gratings like dielectric 23 , 24 or plasmonic 25 structures. Moreover, extensive studies regarding metasurfaces 26 , 27 have been conducted to increase the directional outcoupling of emitters.…”

Up-conversion Luminescence Enhanced by the Plasmonic Lattice Resonating at the Transparent Window of Water

“…Aluminum nanocylinder arrays with various periodicities assembled in the square lattice were fabricated on silica glass substrate using the technique of nanoimprint lithography and reactive ion etching (RIE). 50 An Al layer of 120 nm thickness was deposited on the glass substrate using an electron beam deposition, and then a resist layer of TU2-170 (170 nm) was spin-coated onto the Al film prebaked for 5 min at 95 °C. The resist layer was patterned using the nanoimprint technique (EntreTM3, Obducat).…”

“…Compared to gold, Al is less explored in the study of plasmonic UCL enhancement in spite of its high plasmonic ability and material abundance. Especially when organized in a periodic lattice, the lattice plasmon, that is, the hybridized mode of localized SPRs with in-plane light diffraction, can be excited at the spectral position determined by the periodicity. − The combination of Al nanocylinder arrays with phosphors has been demonstrated to show enhanced down-conversion luminescence. − We optimize the size of each nanocylinder and the periodicity of the lattice to maximize the extinction at 800 nm and thus the UCL intensity. By combining the core–shell NPs with a designed nanocylinder lattice, we can achieve a significant enhancement such as 44-fold for UCL at the green emission branch under λ = 808 nm excitation.…”