Resonant energy transfer properties of perovskite nanocrystals

Perovskite nanocrystals of the form FAPbBr3 display significant promise in the field of optoelectronics. In particular, these nanocrystals could bridge the `green gap' of LED technology, and also serve to down-convert ultraviolet light for harvesting using silicon-based photovoltaic cells. To remain competitive with traditional devices, optimising the energy transfer between the nanocrystal and the device is crucial, however very little investigation has been performed into this subject. Here, we characterise the energy transfer dynamics of FAPbBr3 nanocrystals on a silicon substrate using time resolved photoluminescence. We also use deposited `spacer layers' to vary the displacement of the nanocrystals from the silicon in order to observe the effect on the energy-transfer dynamics. We find that the overall photo luminescent lifetime increases when reducing the distance between between the nanocrystals and the silicon layer, which runs counter to the expected behaviour. This suggests that the presence of an optically-active substrate suppresses photo luminescent lifetime and, further, suggests that nanocrystal-to-nanocrystal transfer is highly efficient.