Emission enhancement in nanoassemblies with extremely small metal nanoparticles: Nonmonotonic effect of temperature and the non-Markovian interactions

Compact light-emitting quantum dot monolayers find wide-ranging applications in photovoltaics to display technology. A key aspect of display technology is the light extraction capability and the quantum efficiency of these layers. The usual Purcell enhancement requiring large-scale proximal metal nanostructures would completely disrupt the packing of such ordered layers and hence cannot be used. In this report, we demonstrate a nonmonotonic temperature dependence of emission enhancement in compact tiny, fully absorbing metal nanoparticle embedded quantum dot layers, which is captured by a non-Markovian treatment of emitter-metal nanoparticle interactions. We also demonstrate how this nonmonotonic behavior with temperature is dominated by the electron-phonon interactions in the metal nanoparticles. Significantly, the observed photoluminescence enhancement maximum of similar to 10 occurs at a temperature of similar to 150 K which is much higher compared to earlier reports. The results suggest the possibility of using our platform in various display, photonic, and sensing devices with higher sensitivity and energy efficiency.