Interfacial Nucleation Seeding for Electroluminescent Manipulation in Blue Perovskite Light-Emitting Diodes

Efficient and stable blue emission of perovskite light-emitting diodes (PeLEDs) is a requisite toward their potential applications in full-color displays and solid-state lighting. Rational manipulation over the entire electroluminescence process is promising to break the efficiency limit of blue PeLEDs. Herein, a facile device architecture is proposed to achieve efficient blue PeLEDs for simultaneously reducing the energetic loss during electron-photon conversion and boosting the light outcoupling. Effective interfacial engineering is employed to manipulate the perovskite crystallization nucleation, enabling highly compact perovskite nanocrystal assemblies and suppressing the trap-induced carrier losses by means of interfacial hydrogen bonding interactions. This strategy contributes to a high external quantum efficiency (EQE) of 12.8% for blue PeLEDs emitting at 486 nm as well as improved operational stability. Moreover, blue PeLEDs reach a peak EQE of 16.8% with the incorporation of internal outcoupling structures for waveguided light, which can be further raised to 27.5% by integrating a lens-based structure for substrate-mode light. These results verify the validity of this strategy in producing efficient and stable blue PeLEDs for practical applications.