High Quantum Yield Blue InP/ZnS/ZnS Quantum Dots Based on Bromine Passivation for Efficient Blue Light-Emitting Diodes

Red and green InP quantum dots (QDs) already have been demonstrated with excellent luminescence performance closing the gap with CdSe-based QDs. However, the performance of blue InP QDs still lags behind that of red and green QDs. For blue InP QDs synthesized by aminophosphine and zinc iodide, the inherent I- possesses weak passivation ability. By introducing Br- with a smaller ion radius and larger binding energy, the quantum yield of blue InP QDs is increased from 54% to 93%, which is the highest value reported so far. Meanwhile, the long-chain 1-dodecanethiol is replaced by the short-chain 1-octanethiol through ligand exchange to increase the carrier injection efficiency. The blue quantum dot light-emitting diodes (QLEDs) made of these QDs showed an external quantum efficiency of 2.6%, which is notably the highest blue InP QLED reported so far.