Active control over exciton (electron-hole pair) transport is a much sought-after goal to create reconfigurable excitonic and optoelectronic transistors. The PAQM team achieved the first example of predictive optical control over exciton transport in semiconductors.
Superatomic materials are ideal for active control over electronic properties. The electronic coupling between superatom clusters is strongly modulated by inter-cluster distance and relative orientation. Phonons (vibrations) that delocalize over more than a single cluster can therefore strongly perturb inter-cluster electronic coupling, which in turn will modulate exciton transport properties.
Here the PAQM team successfully exploited these electron–phonon interactions to control exciton transport in the superatomic semiconductor Re6Se8Cl2 at room temperature. Using ultrafast optical excitation of coherent phonons in thin flakes of Re6Se8Cl2, the team achieved a >60-fold improvement in exciton propagation length (limited by sample size), and importantly gained the entirely new ability of optically switching and directing this long-range transport toward any chosen target site.