The fabrication of large-area blue-light perovskite light-emitting diodes (PeLEDs) in the air environment will significantly promote the commercialization of perovskite-based optoelectronic devices in display applications. However, under the influence of ambient humidity, perovskite ion crystals will undergo a dynamic formation and degradation process, resulting in uneven morphology and a large number of defects in perovskite films, and the performance of large-area blue devices is poor.
In view of this, recently, the team of Associate Professor Wang Hongyue & Professor Wang Hongqiang from the School of Materials Science and Technology of Northwestern Polytechnical University has developed a new two-way embedded anchoring control strategy, which realizes the synergistic regulation of HTL and perovskite active layers by planting zwitterionic polymer brush PEIS in the inorganic hole transport layer NiOx, in which the embedded part of the polymer brush in HTL can passivate the surface defects of NiOx nanoparticles and promote carrier injection. The part embedded in the active layer can promote the uniform nucleation of perovskites under environmental conditions, and precisely control the growth rate of different n-phases of blue quasi-two-dimensional perovskites, which can improve the uniformity and luminescence of perovskite films (Fig. 1). After the introduction of PEIS molecules, the roughness of the embedded interface was effectively reduced, and a uniform perovskite nucleation site was exhibited (Fig. 2). When the PEIS doping content is 0.5%, a quasi-two-dimensional perovskite crystallization kinetics is formed with n=3 as the dominant and the other n-phases with similar crystallization rates, which improves the luminescence ability and uniformity of the quasi-two-dimensional blue perovskite films prepared in the air environment (Fig. 3). This work is the first to realize the preparation of large-area (2 cm × 2 cm) blue perovskite light-emitting diodes in ambient air (Fig. 4), which provides a new idea for controlling the crystallization kinetics of perovskite in the air environment and promotes the commercial application of perovskite luminescent materials in the display field. The work was published in Angew. Chem., Int. Ed. (DOI: 10.1002/anie.202411361). The first authors of the article are Wu Jiandong and Li Huixin, doctoral students of Northwestern Polytechnical University, and the corresponding authors are Associate Professor Wang Hongyue and Professor Wang Hongqiang of Northwestern Polytechnical University. The above research was supported by the National Natural Science Foundation of China (No. 22372132), National Key R&D Program (No. 2023YFE0206300) and other projects.
Figure 1: Schematic diagram of a bidirectional embedded anchor interface
Figure 2: NiOx-PEIS embedded interface with low roughness and perovskite homogeneous nucleation sites
Figure 3: PEIS exhibits an elongated molecular conformation in a perovskite film
Figure 4: Control of the crystallization rate of each n-phase of a quasi-2D perovskite at the NiOx-PEIS interface
Figure 5: Large-area blue perovskite light-emitting diodes prepared in an air environment
Summary: The authors demonstrate that the PEIS-modified NiOx hole transport interface has good flatness and uniform abundant perovskite nucleation sites, and realizes the precise control of the crystallization growth kinetics of different n phases of quasi-two-position blue light perovskite films in the air environment. The enhanced interfacial contact between the perovskite luminescent layer and the PEIS transport layer effectively improves the PLQY and environmental stability of the perovskite film. Thanks to the controllable crystallization process of perovskite on PEIS-NiOx substrate, the team achieved the first time to fabricate large-area blue perovskite light-emitting diodes in ambient air. When the emission area of the device is 0.2 × 0.2 cm2, the peak EQE of the device is 2.34%, and the maximum brightness is 1161 cd m−2. When the emission area is 1 × 1 cm2, the peak EQE of the device is 2.09%, and the maximum brightness is 624 cd m−2. When the emission area is 2 × 2 cm2, the peak EQE of the device is 0.80%, and the maximum luminous emission is 734 cd m−2. This work provides a new idea for controlling the crystallization kinetics of perovskites in the air environment, and paves the way for the commercialization of perovskites in displays.
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Original link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202411361 Source: Frontiers of Polymer Science