Compared with green and red perovskite light‐emitting diodes (PeLEDs), the development of blue PeLEDs has been lagging due to high defect density and inferior carrier transport. Herein, a novel defect‐passivation strategy is proposed to fabricate efficient sky‐blue PeLEDs by using isocyanate molecules. This strategy not only significantly reduces the nonradiative recombination loss caused by defects but also improves the injection and transport capacities of carriers by reducing the confinement effect. Benefiting from the passivation engineering and the reduction of confinement effect, the prepared sky‐blue PeLEDs present a significantly improved external quantum efficiency of 12.5% at 489 nm, which is 1.5 times higher than that of the control device. Meanwhile, the universality of isocyanate‐based passivators to improve the performance of PeLEDs is also demonstrated. The finding of this study provides a new reference for the selection of novel passivation agents to construct highly efficient blue PeLEDs.

The substrates of conventional flexible perovskite solar cells (FPSCs) are thermoplastic polymer material polyethylene naphthalate (PEN), which will deform during high temperature annealing process. In addition, lead iodide (PbI2) permanently formed and the substrate undergoes reversible deformation from 20 °C to 200 °C and back to 20 °C. Therefore, to balance the substrate supporting capacity and the crystalline quality of narrow band gap α‐phase formamidinium lead iodide (α‐FAPbI3), an annealing process of 120 °C for 30 minutes is determined. Additionally, there will also be a large number of gaps and lattice strain at the perovskite grain boundaries during the annealing process as the FAPbI3 phase transition is accompanied by much lattice shrinkage. As a result, 1,6‐hexanediammonium diiodide (HADI) is chosen to passivate the defects and release the stress of perovskite film. Therefore, a recorded 1.4% extended stretch rate of the flexible film is attained. Finally, the champion PCE of 21.14% under AM 1.5G and 31.52% under 1062 lux is achieved after HADI treatment, accompanied by a better long‐term and mechanical stability. This study provides annealing process optimization and stress relief strategies for the further development of narrow band gap FPSCs.

Despite the promising charac-teristics of tin-based perovskite solar cells (TPSCs), one obvi-ous limitation is the rapid oxi-dation of Sn2+, resulting in poor device performance and stabil-ity. Here, we introduced differ-ent...

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Organic‐inorganic hybrid perovskite solar cells (PSCs) with unique properties exhibit their powerful competitiveness in the photovoltaic field over the past few years. However, the challenges of stability for perovskite devices limit the commercialization and further development. The 2D/3D hybrid structures combine the superior efficiency of bulk perovskites and the superior stability of layered perovskites and gradually get hotspots of the photovoltaic field. In addition, there remains a lack of comprehensive understanding and systematic summary of the function of 2D perovskite attributed to the complex nature of 2D/3D structures. Here, the latest progress of 2D/3D hybrid structures and focus on the functionality of 2D phases in mixed structures and the underlying mechanism from the perspective of their different distributions in the perovskite layer is summarized. Then, the insight and vital factors for overall improvements in the stability of 2D/3D structures are thoroughly discussed. Finally, it is expected that this review will contribute to the present challenges and future research prospects in the photovoltaic industry.