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

• Published in: Organic electronics Vol. 70; pp. 140 - 148
• Main Authors: Zhiwei, Ma, Liping, Tang, Bingbing, Lyu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2019
• Subjects: Photoluminescence enhancement; Post-treatment; Quantum dots light emitting diodes; Surface defects; Quantum dots light emitting diodes; Photoluminescence enhancement; Post-treatment; Surface defects
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2019.04.014

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 co-treatment), and their quantum yields and stability are improved. Here we report all solution-processed multilayer 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. [Display omitted] •Quantum dots surface passivation engineering improved their quantum yields.•By the synergistic effect, quantum dots transient PL decay dynamics turned from double to mono-exponential decay.•After quantum dots post-treatment, the R/G/B QD-LEDs of EQE reached up to 14.4%, 15.9% and 14.7%, respectively.