Lead Halide Perovskites for Blue Light‐Emitting Diodes: Advances, Challenges, and Prospects

Abstract Lead halide perovskites (LHPs), celebrated as “super‐star” materials with exceptional optoelectronic properties, possess great potential in next‐generation high‐definition displays. Recently, the external quantum efficiencies (EQEs) of red‐ and green‐emitting LHP‐based devices already met the criteria for commercial applications. Nevertheless, the performance of blue LHP devices lags far behind that of their red/green counterparts, seriously hindering the implementation of perovskite light‐emitting diodes (PeLEDs) in full‐color displays. Although some reported blue PeLEDs have EQEs exceeding 25%, blue‐light devices still encounter crucial bottlenecks such as short operational lifetimes and emission peaks noncompliant with the standards for high ‐ definition displays. The review focuses on the progress of blue PeLEDs with two primary types of emissive layers (EMLs): perovskite nanocrystals and perovskite polycrystalline thin films. A classified review of blue light emission achieved through mixed halogens and quantum confinement effects is conducted. Based on this discussion, the critical challenges faced by blue PeLEDs are explored and promising research directions to tackle these challenges in future are prosed. Finally, a forward‐looking perspective is delivered by comparing and evaluating the respective advantages and disadvantages of the two primary EML types, while also introducing novel perovskite structural designs and their prospects for future optoelectronic applications.