All‐inorganic and lead‐free CsSnI3 is emerging as one of the most promising candidates for near‐infrared perovskite light‐emitting diodes (NIR Pero‐LEDs), which find practical applications including facial recognition, biomedical apparatus, night vision camera, and Light Fidelity. However, in the CsSnI3‐based Pero‐LEDs, the holes injection is significantly higher than that of electrons, resulting in unbalanced charge injection, undesired exciton dissipation, and poor device performance. Herein, it is proposed to manage charge injection and recombination behavior by tuning the interface area of perovskite and charge‐transporter. A dendritic CsSnI3 structure is prepared on the hole‐transporter, only making a bottom contact with the hole‐transporter and exposing all other available crystal surfaces to the electron‐transporter. In other words, the interface area of perovskite/electron‐transporter is significantly higher than that of perovskite/hole‐transporter. Moreover, the embedding interface of perovskite/electron‐transporter can spatially confine holes and electrons, increasing the radiation recombination. By taking advantage of the dendritic structure, efficient lead‐free NIR Pero‐LEDs are achieved with a record external quantum efficiency (EQE) of 5.4%. More importantly, the dendritic structure shows great superiorities in flexible devices, for there is almost no morphology change after 2000‐cycles of bends, and the fabricated Pero‐LEDs can keep 93.4% of initial EQEs after 50‐cycles of bends.

Perovskite light‐emitting diodes (Pero‐LEDs) have attracted significant attention due to their high color purity and solution processing, presenting potential applications for next‐generation solid‐state lighting and displays. Continued materials development has shown that passivating non‐radiative defects can improve device performance. In theory, CsPbBr3&Cs4PbBr6 should be a model emitter for Pero‐LEDs, as its lattice matching provides ideal passivation and efficient exciton confinement. However, the low charge transport of Cs4PbBr6 has so far hindered device performance. Herein, a dual‐phase regulation method to grow a CsPbBr3&Cs4PbBr6 perovskite layer that enables efficient electrical injection is developed. This leads to the realization that Pero‐LEDs with a maximum EQE of 22.3% with a luminance of 10,050 cd m−2, and the devices show a T50 of 59 h at 130 cd m−2.

Over the past several years, perovskite‐based luminescent materials and devices have attracted considerable research interest and achieved superior performance, including red/near‐infrared, green, and blue regions. Despite the abundant research progress in the above‐mentioned luminous regions, studies on cyan‐emitting perovskites are still lacking. However, cyan‐emitting perovskite materials are of great importance and have many promising applications, especially for high‐quality lighting and light communication. Herein, the recent research progress on perovskite with cyan emission is summarized, including the preparation methods and improvement on device performance. The preparation strategies are categorized into compositional engineering, dimensional engineering, and size engineering. The corresponding device performance is displayed too. Furthermore, the strategies of performance enhancement and future perspectives are proposed in the end. There is hope that this minireview can trigger more attention to this particular emitting region.

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