Highly efficient full color light-emitting diodes based on quantum dots surface passivation engineering

High-efficiency quantum dots light-emitting diodes have been showing promise in the development of optoelectronic devices in displays and solid-state lighting. However, quantum dots surface traps strongly quench its luminescence when transfer it from in solution into on film. We propose a reproducible method of studying photoluminescence decay dynamics in nanocrystals by implementing surface passivation engineering, the results reveal that quantum dots surface traps-being the main cause of the fluorescence quenching and non-radiative recombination-could be eliminated by a series of surface post-treatment processes. Moreover, we study the quantum dots transient fluorescence spectra that the PL decay channel turned from the double exponential decay (control) to the mono-exponential decay kinetics (both the green and red quantum dots with UV-water cotreatment), and their quantum yields and stability are improved. Here we report all solution-processed multi-layer monochromatic quantum dots light-emitting diodes what the emitting layer is formed from the surface post-treated red/green/blue quantum dots. These devices have exhibited a maximum current efficiency and external quantum efficiencies (EQE) of 20.7 cd/A and 14.4% for red, 65.1 cd/A and 15.9% for green, and 4.8 cd/A and 14.7% for blue devices, respectively. We expect the successful quantum dots surface passivation engineering would exert profound influence on their applications to light emitting devices.