Perovskite quantum dots are semiconductor crystals just a few nanometres across whose quantum-confined electrons absorb and re-emit light with remarkable efficiency, making them candidates for LEDs, photocatalysis and future quantum light sources. They are cheap to synthesise in solution, but their soft ionic lattices disintegrate in polar solvents such as alcohols, a serious obstacle to practical processing. A team led by Quinten Akkerman at LMU's Nano-Institute has now tackled the problem from two directions.
In ACS Energy Letters, the researchers describe Gemini ligands that grip the dot surface with charged groups while presenting a polar face to the outside world. The shell, only about 0.7 nanometres thick, lets the dots disperse stably in green solvents such as ethanol while keeping their high photoluminescence quantum yields, a combination that matters for environmentally benign optoelectronic manufacturing.
A companion paper in the Journal of the American Chemical Society shows how to grow the dots with sub-unit-cell precision. By suppressing the formation of new seed crystals and sustaining growth through a multi-stage injection strategy, the team produced dots with narrow size distributions and stable optical properties, the parameters that set emission colour and intensity. Together, the studies open routes to better LEDs and finely tuned quantum light technologies.