Strain Tuning of Energy Transfer from 0D to 2D

We probe the effect of mechanical strain on the non-radiative energy transfer (NRET) rate from a 0-dimensional material, CdSe/ZnS quantum dot (QD), to a 2-dimensional material, monolayer (1L) WS₂. Our calculations show that the NRET rate is enhanced as the emission spectrum of CdSe/ZnS QD overlaps with the exciton resonances of 1L WS₂. On that basis, the NRET rate is strongly dependent on the magnitude of strain, since applying strain shifts the exciton energies in 1L WS₂. Based on the experimental results in the literature, we have computed the strain-dependent dielectric function of WS₂. We calculate the NRET rate as a function of uniaxial strain and show that it can be greatly tuned by purely mechanical means. We choose WS₂ among the commonly used semiconducting group-6 transition metal dichalcogenides; WSe₂, MoS₂, MoSe₂, MoTe₂ as it has the smallest A exciton linewidth at room temperature, which is relatively less sensitive to strain. Our results exemplify the use of mechanical strain as a means of shedding light on the interaction between low-dimensional material systems. We will follow up with experiments in which we will deposit quantum dots on 2D materials and perform photoluminescence spectroscopy to demonstrate the strain-engineered NRET in QDs.