Strain tuning the nonradiative energy transfer rate from quantum dots to WS2

This research investigates the effect of strain on the nonradiative energy transfer (NRET) rate between quantum dots (QDs) and bilayer (2L) WS2, aiming to enhance our understanding of exciton dynamics in these hybrid systems. We initially calculated the NRET rate theoretically, expecting a decrease with increasing strain due to reduced overlap between the emission and absorption spectra. However, our experimental results showed the opposite trend. Time-resolved photoluminescence (TRPL) measurements revealed a decrease in exciton lifetime for QDs on 2L WS2 under strain, indicating a more significant influence of nonradiative decay pathways, which was unexpected based on our theoretical calculations. Photoluminescence (PL) experiments under strain also showed a reduction in the integrated PL spectra, suggesting increased NRET efficiency with strain. In addition to strain effects, we examined how the thickness of WS2 influences NRET. TRPL measurements showed that the exciton lifetimes of QDs on 2L WS2 (0.78 ns) and bulk WS2 (2.64 ns) were shorter compared to QDs on PETG (3.24 ns), confirming that NRET is faster in 2L WS2 than in bulk WS2. These findings align with trends observed in existing literature. Before addressing the discrepancies between theoretical predictions and experimental data, future studies should prioritize conducting additional experiments to validate our findings further