No abstract

A resin overcoat allows effective control over the crystallization of hollow titania nanoshells during calcination and enhances their photocatalytic activity.

Luminogens with colorful ultralong organic phosphorescence (UOP) are in high demand because of various potential applications in optoelectronics. Herein, we report a concise approach to tune UOP based on the same chromophores of carbazole and phthalimide units through alkyl engineering. With flexible alkyl increase, UOP emission colors can be controllably tuned from green to orange along with lifetime variation. Furthermore, these phosphors were endowed with unexpected visible-light excitation, mechanochromism, and mechanoluminescence properties simultaneously. Additionally, colorful UOP with diverse emission lifetime was first applied to the 4D code for information encryption. These findings will open a door to explore multifunctional organic phosphorescence materials and expand their potential applications.

Amorphous purely organic phosphorescence materials with long‐lived and color‐tunable emission are rare. Herein, we report a concise chemical ionization strategy to endow conventional poly(4‐vinylpyridine) (PVP) derivatives with ultralong organic phosphorescence (UOP) under ambient conditions. After the ionization of 1,4‐butanesultone, the resulting PVP‐S phosphor showed a UOP lifetime of 578.36 ms, which is 525 times longer than that of PVP polymer itself. Remarkably, multicolor UOP emission ranging from blue to red was observed with variation of the excitation wavelength, which has rarely been reported for organic luminescent materials. This finding not only provides a guideline for developing amorphous polymers with UOP properties, but also extends the scope of room‐temperature phosphorescence (RTP) materials for practical applications in photoelectric fields.

Provided here is evidence showing that the stacking between triplet chromophores plays a critical role in ultralong organic phosphorescence (UOP) generation within a crystal. By varying the structure of a functional unit, and different on‐off UOP behavior was observed for each structure. Remarkably, 24CPhCz, having the strongest intermolecular interaction between carbazole units exhibited the most impressive UOP with a long lifetime of 1.06 s and a phosphorescence quantum yield of 2.5 %. 34CPhCz showed dual‐emission UOP and thermally activated delayed fluorescence (TADF) with a moderately decreased phosphorescence lifetime of 770 ms, while 35CPhCz only displayed TADF owing to the absence of strong electronic coupling between triplet chromophores. This study provides an explanation for UOP generation in crystal and new guidelines for obtaining UOP materials.