Temperature-tuning of near-infrared monodisperse quantum dot solids at 1.5 μm for controllable Förster energy transfer

We present the first time-resolved cryogenic observations of Förster energy transfer in large, monodisperse lead sulfide quantum dots with ground-state transitions near 1.5 μm (0.8 eV), in environments from 160 K to room temperature. The observed temperature-dependent dipole-dipole transfer rate occurs in the range of (30-50 ns) ^-1, measured with our confocal single-photon counting setup at 1.5μm wavelengths. By temperature-tuning the dots, 94% efficiency of resonant energy transfer can be achieved for donor dots. The resonant transfer rates match well with proposed theoretical models.