For the state-of-the-art quantum dot light-emitting diodes, while the ZnO nanoparticle layers can provide effective electron injections into quantum dots layers, the hole transporting materials usually cannot guarantee sufficient hole injection owing to the deep valence band of quantum dots. Developing proper hole transporting materials to match energy levels with quantum dots remains a great challenge to further improve the device efficiency and operation lifetime. Here we demonstrate high-performance quantum dot light-emitting diodes with much extended operation lifetime using quantum dots with tailored energy band structures that are favorable for hole injections. These devices show a T₉₅ operation lifetime of more than 2300 h with an initial brightness of 1000 cd m⁻², and an equivalent T₅₀ lifetime at 100 cd m⁻² of more than 2,200,000 h, which meets the industrial requirement for display applications.

The low efficiency and fast degradation of devices from ink-jet printing process hinders the application of quantum dot light emitting diodes on next generation displays. Passivating the trap states caused by both anion and cation under-coordinated sites on the quantum dot surface with proper ligands for ink-jet printing processing reminds a problem. Here we show, by adapting the idea of dual ionic passivation of quantum dots, ink-jet printed quantum dot light emitting diodes with an external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours were reported for the first time. The liquid phase exchange of ligands fulfills the requirements of ink-jet printing processing for possible mass production. And the performance from ink-jet printed quantum dot light emitting diodes truly opens the gate of quantum dot light emitting diode application for industry.

Thin-film encapsulation has been a critical method to realize small-size OLED displays. However, the manufacturing of large-size flexible OLED is still in the preparatory phase prior to commercialization, which entails more rigorous demands for reliability and flexibility with regard to thin-film encapsulation. This review, from the perspective of engineering for mass production, addresses the development of thin-film encapsulation and its three core properties for comprehensive validation while engineering, including basic properties, reliability, and compatibility. Moreover, considering the prospective evolution of display products, the review on novel thin-film encapsulation was conducted to evaluate the potential engineering value for thinning, ultra-flexibility, multifunctionality, novel equipment, and emerging technology. It is anticipated that some of the aforementioned technologies may prove to be of significant engineering value. It is therefore hoped that by comprehensive engineering verification, the commercial application of novel thin-film encapsulation can be promoted and the competitiveness of OLED products can be effectively enhanced.