Small‐Molecule‐Doped Organic Crystals with Long‐Persistent Luminescence

Abstract

Traditional long-persistent luminescence (LPL) materials, which are based on inorganic systems containing rare elements and with preparation temperatures of at least 1000 °C, exhibit afterglow times of more than 10 h and can be tuned for different applications. However, the development of this field is hindered due to the large thermal energy consumption and the need for nonrenewable resources. Thus, the development of a "green" design and preparation of LPL materials is of some importance. A doped-crystalline material based on two metal-free organic small molecules is easily prepared through ultrasonic crystallization at room temperature. It has a high-quality, singlecrystalline structure, and visible LPL performance with a duration of more than 6 s upon low-energy photoexcitation. A green, flexible, and convenient screen-printing technology for controllable pattern anticounterfeiting is then developed from this purely organic material, which improves the prospects for commercial utilization in the future.

TADF‐Type Organic Afterglow

“…[30][31][32][33] Supramolecular interactions such as inclusion complexation and hydrogen bonding have also been reported to suppress the molecular vibrations of the triplet excited state of the luminescent component to increase F P of room-temperature phosphorescence and afterglow materials. [34][35][36][37][38][39][40] Besides molecular design, aggregation state control and supramolecular assembly, [41][42][43][44][45][46][47][48] two-component design strategies developed by us and other research groups, [49][50][51][52][53][54] where asecond component is employed to control the excited state properties of luminescent component (i.e., the first component), have been shown to enhance the room-temperature phosphorescence and afterglow efficiency.For example,inthe dopant-matrix system, the rigid microenvironment provided by the matrix molecules can inhibit the nonradiative deactivation of the triplet excited states of the dopant molecules, [55,56] and the deuteration of the dopant molecules can further inhibit the vibration of the triplet excited states, leading to the formation of efficient room-temperature afterglow materials. [57] In the co-crystal system, F P as high as 55 %has been achieved through the cooperation of internal and external HAE, whereas t P was reduced to approximately 10 ms. [22] In the donor-acceptor system, the excitation light can cause charge separation, while the charge recombination was strongly suppressed in solid medium, giving rising to organic long persistent luminescence (OLPL) up to hours.…”

Recent Advances of Persistent Luminescence Nanoparticles in Bioapplications

“…Yang et al reported a new type of metal-organic frameworks (MOFs) with long-lasting afterglow which showed highly tunable afterglow phosphorescence colors upon pyridine solution treatment. This finding supplies a group of MOFs-based persistent luminescence nanophosphors with high performance [150][151][152][153][154]. Up to now, the afterglow MOFs have not been used in biomedical fields in vivo due to the relatively short emission wavelength and the undesirable diameter.…”

Time‐Dependent Afterglow Color in a Single‐Component Organic Molecular Crystal

“…Molecular organic materials with long‐persistent luminescence at room temperature have potential applications in anticounterfeiting, information storage, data encryption, and bioimaging, and have thus attracted considerable interest in the past decade . Several organic RTP materials with ultralong lifetime have been reported . Huang and An et al.…”