Distance-Engineered Plasmon-Enhanced Light Harvesting in CdSe Quantum Dots

Improvement of light harvesting in semiconductor quantum dots (QDs) is essential for the development of efficient QD-based solar energy conversion systems. In this study, plasmon-enhanced light absorption in CdSe QDs sensitized on silver (Ag) nanoparticle (NP) films was examined as a function of interparticle (QD to Ag NP) distance. Up to 24-fold plasmonic enhancement of fluorescence from QDs was observed when the particle separation distance was ≥5 nm. The enhancement effect was observed to largely sustain the exciton lifetimes in QDs and to strongly depend on the incident photon wavelength following the plasmon resonant strength of Ag NPs, confirming that the enhanced photoluminescence was mainly due to the enhancement in photoabsorption in CdSe QDs by the plasmon of Ag NPs. This study suggests applications of Ag NPs in QD-based solar energy conversion for significantly improving light harvesting in QDs.