Ultralong MRTADF and Room‐Temperature Phosphorescence Enabled Color‐Tunable and High‐Temperature Dual‐Mode Organic Afterglow from Indolo[3,2‐b]carbazole

In recent years, there is a growing interest in developing ultralong organic room‐temperature phosphorescence (ORTP) with lifetimes in the range of seconds. As one of the important three primary colors, ultralong blue ORTP is an indispensable core component in RTP regulation and application, however, the large Stokes shift characteristics pose certain challenges in developing ultralong blue ORTP. Here, a new family of blue phosphors are synthesized and ultralong blue ORTP are realized through crystal assembly in water and organic phase. Remarkably, compared to crystal materials obtained in organic phases, assembly materials obtained in water enabled long‐lived blue ORTP with lifetimes up to 2.3 s and phosphorescence quantum yield reached as high as 29.27%. In addition to the efficient and green assembly form, such dark blue ORTP materials possessed high thermal stability and flexible tunability. Moreover, the superiority of the selected assembly components is demonstrated by comparing them with polymer assembly and the proposed blue ORTP materials show great potential in an organic programmable information encryption/anti‐counterfeiting.

Ultralong Blue Organic Room‐Temperature Phosphorescence Promoted by Green Assembly

Chen,

Zhu

et al. 2024

Host‐Guest Systems Enable Efficient Organic Afterglow via a Facile Spraying Method

Man,

Chen,

Tao

et al. 2024

Unlocking the afterglow properties of the fluorescence molecules at room temperature is an urgent challenge. Herein, inks prepared with dimethyl terephthalate (DTT) and carbazole (Cz) analogs with heteroatom (C, S, and O) substituents on the N as host and guest molecules can be directly sprayed onto different substrates to unlock the excitation‐wavelength dependent (Ex‐De) afterglow characteristics of the guest compound. Additionally, with the increase in the number of lone pair electrons, spin‐orbit coupling (SOC) increases, resulting in a longer afterglow duration lasting up to 4.5 s with Φp>27%. Theory calculations and experiments indicate that the afterglow originated from the interactions between the host and guest molecules restricting the non‐radiative transition of the triplet excitons. Different Ex (with watershed at 310 nm) lead to the variation in the conformation of the S0DTT and S1DTT, which in turn affects the strength of host‐guest interactions and contributes to the Ex‐De characteristics. Benefiting from facile preparation, substrate‐independent applicability, and Ex‐De characteristics, the afterglow samples are demonstrated for applications in multilevel information security fields. This work proposes a general strategy for unlocking the afterglow emission of traditional molecules, which is valuable for the discovery of high‐performance afterglow materials in the future.

Luminous Fish‐Inspired Hydrogels with Underwater Long‐Lived Room Temperature Phosphorescence

Chen,

Qie,

Yang

et al. 2024

Some marine animals form long‐lived luminescence for predation, communication, camouflage, and anti‐predation. These marine animals demonstrate soft nature, sustainable glowing, and underwater emission, which are difficult to achieve in synthetic room temperature phosphorescence (RTP) materials. Inspired by these marine animals, here the study reports RTP hydrogels that show long‐lived phosphorescence (lifetime >500 ms and afterglow >10 s) in water. Exceptional underwater mechanical properties are simultaneously achieved, including tensile strength of 5.1 MPa, tensile strain of 452%, and toughness of 19.3 MJ m−3. The key to this achievement lies in the in situ phase separation microarchitecture formed between polyacrylamide (PAM) and its partial hydrolysates, which confines the motions of polymer chains and protects vulnerable triplet excitons from quenching of water. Such a strategy shows the merits of facile fabrication without laborious synthesis. In addition, these RTP hydrogels offer repeatable photoprinting and highly stability in water, providing a versatile platform for underwater applications of RTP materials, including information encryption and camouflage of marine animals.