Thermomechanical control of electronic coupling in quantum dot solids

We show that electronic coupling in quantum dot solids can be controlled thermomechanically. The amount and nature of interstitial material controls the shrinkage of the solids upon cooling and thereby the distances as well as electronic coupling between the constituting semiconductor nanocrystals. Using photoluminescence and transmission electron microscopy at variable temperatures we apply this concept to single nanowires and densely packed nanocrystals. We tune the band gap emission and realize both temperature-induced red- and blueshifts.