Luminescence of biexcitons in CuBr quantum dots

Abstract

In this contribution, luminescence experiments at CuBr quantum dots grown in a wide range of sizes in the weak confinement regime (R≥a B ) will be presentod. In intensity-dependent luminescence measurements with ns-pulses, for each dot size two peaks can be resolved and are attributed to exciton and biexciton transitions, respectively. From time-resolved luminescence after ps-excitation, we obtain additional insight into the dynamics of biexciton formation and decay. We observe a delayed onset and a faster decay of the biexciton luminescence compared to the exciton luminescence. The experimental values for the energetic difference of the exciton and the biexciton peak agree very well with recent numerical calculations for the biexciton binding energy, predicting an increase for decreasing dot sizes. An exception are very small dots where e.g. due to interface-related states these calculations can no longer be applied