In order to find a response, the researchers performed in-depth systematic finite-difference time domain simulations of excitation, spontaneous emission, and quantum efficiency enhancement for a number of metallic nanostructures, seeking to exploit so-called surface plasmonic resonances when nanoscale metallic structures are exposed to light. Depending on the metal, the size, and the shape, the properties of metallic structures vary.
They found that they could significantly enhance the fluorescence intensity of colloidal green and red QDs when those were coupled with aluminum (Al) and silver (Ag) nanodisk (ND) arrays, alleviating the loss of QDs and their quantum yields during fabrication processes, such as patterning and spin-coating.
Through simulation, the researchers calculated that they could enhance overall photoluminescence from a 500×500µm2 substrate by a factor of 2.37 and 2.82, using Al ND-green QD and Ag ND-red QD structures, respectively, matching closely their experimental results.
Using different metallic nanostructures for each QD LED (silver nanodisks for Red QDs and aluminum nanodisks for Green GDs) to enhance their fluorescence translates into reduced production costs (using fewer QDs) while improving the efficiency of the QD LEDs.
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