Compared to efficient green and near‐infrared light‐emitting diodes (LEDs), less progress has been made on deep‐blue perovskite LEDs. They suffer from inefficient domain [various number of PbX6− layers (n)] control, resulting in a series of unfavorable issues such as unstable color, multipeak profile, and poor fluorescence yield. Here, a strategy involving a delicate spacer modulation for quasi‐2D perovskite films via an introduction of aromatic polyamine molecules into the perovskite precursor is reported. With low‐dimensional component engineering, the n1 domain, which shows nonradiative recombination and retarded exciton transfer, is significantly suppressed. Also, the n3 domain, which represents the population of emission species, is remarkably increased. The optimized quasi‐2D perovskite film presents blue emission from the n3 domain (peak at 465 nm) with a photoluminescence quantum yield (PLQY) as high as 77%. It enables the corresponding perovskite LEDs to deliver stable deep‐blue emission (CIE (0.145, 0.05)) with an external quantum efficiency (EQE) of 2.6%. The findings in this work provide further understanding on the structural and emission properties of quasi‐2D perovskites, which pave a new route to design deep‐blue‐emissive perovskite materials.

Long-lived room temperature phosphorescence (LRTP) is an attractive optical phenomenon in organic electronics and photonics. Despite the rapid advance, it is still a formidable challenge to explore a universal approach to obtain LRTP in amorphous polymers. Based on the traditional polyethylene derivatives, we herein present a facile and concise chemical strategy to achieve ultralong phosphorescence in polymers by ionic bonding cross-linking. Impressively, a record LRTP lifetime of up to 2.1 s in amorphous polymers under ambient conditions is set up. Moreover, multicolor long-lived phosphorescent emission can be procured by tuning the excitation wavelength in single-component polymer materials. These results outline a fundamental principle for the construction of polymer materials with LRTP, endowing traditional polymers with fresh features for potential applications.

Integration of FexS electrocatalysts and simultaneously generated interfacial oxygen vacancies was designed to promote the water splitting performance of Fe2O3 photoanodes.