The study of purely organic room‐temperature phosphorescence (RTP) has drawn increasing attention because of its considerable theoretical research and practical application value. Currently, organic RTP materials with both high efficiency (ΦP > 20%) and a long lifetime (τP > 10 s) in air are still scarce due to the lack of related design guidance. Here, a new strategy to increase the phosphorescence performance of organic materials by integrating the RTP host and RTP guest in one doping system to form a triplet exciplex, is reported. With these materials, the high‐contrast labeling of tumors in living mice and encrypted patterns in thermal printing are both successfully realized by taking advantage of both the long afterglow time (up to 25 min in aqueous media) and high phosphorescence efficiency (43%).

Persistent room-temperature phosphorescence (p-RTP) has drawn extensive attention due to its unique photophysical processes and promising applications in organic light-emitting diodes (OLEDs), [1] biological areas, [2] chemical sensors, [3] optics, [4] and anticounterfeiting technology. [5] Currently, p-RTP systems, however, are normally restricted to inorganic compounds. [6] As promising alternatives, pure organic p-RTP luminogens take advantages of low cost, wide variety, environmental friendliness, good biocompatibility, appreciable stability, and good processability, [7] allowing a wide range of optoelectronic and biological applications. [2] The triplet excitons of organic luminogens, however, are prone to nonradiative relaxations through vibrational stretching and external quenching (i.e., O 2 ), making it difficult to achieve efficient p-RTP. [8] To overcome such barriers, generally, two attempts are endeavored: one is to boost the spin-orbital coupling (SOC) and subsequently promote the intersystem crossing (ISC) processes through incorporation of heavy atoms, [9] heteroatoms, [10] or aromatic carbonyls; [11] the other is to stabilize the triplet excitons in a rigid environment by suppressing nonradiative decay pathways to activate the RTP emission, [12] such as crystal formation, [13] embedding into rigid hosts, [14] polymer assistance, [15] and metal-organic framework (MOF) coordination. [16] Despite exciting advancements have been made in the past few years, fabrication of efficient and robust p-RTP still remains a challenge. First, the p-RTP efficiency (Φ p ) of reported phosphors with the lifetime (〈τ〉 p ) of several hundred milliseconds are generally below 5%, [11a,13a] and moreover, robust p-RTP at complex and changing environments is rare, even though it is essential for diverse applications in data recording, encryption, anticounterfeiting, and bioimaging. [17] For example, when applied in molecular imaging, owing to their long-lasting nature, p-RTP materials can eliminate the need for light irradiation and circumvent the troublesome interference of nanosecond tissue autofluorescence, thus permitting much clearer and more reliable bioimaging with high signal-to-noise ratios. Current methodologies toward biomedical applications, however, mainly adopt nanocrystallization or top-down nanoparticle Pure organic persistent room-temperature phosphorescence (p-RTP) under ambient conditions is attractive but challenging due to the slow intersystem crossing process and susceptibility of triplet excitons. Fabrication of pure organic RTP luminogens with simultaneously high efficiency and ultralong lifetime still remains a daunting job, owing to their conflicting requirements for the T 1 nature of (n,π*) and (π,π*) characteristics, respectively. Herein, a group of amide-based derivatives with efficient p-RTP is developed through the incorporation of spin-orbital-coupling-promoting groups of carbonyl and aromatic π units, giving impressive p-RTP with lifetime and efficiency of up to 710.6 ms and 10.2%,...

Organic near-infrared room temperature phosphorescence materials have unparalleled advantages in bioimaging due to their excellent penetrability. However, limited by the energy gap law, the near-infrared phosphorescence materials (>650 nm) are very rare, moreover, the phosphorescence lifetimes of these materials are very short. In this work, we have obtained organic room temperature phosphorescence materials with long wavelengths (600/657–681/732 nm) and long lifetimes (102–324 ms) for the first time through the guest-host doped strategy. The guest molecule has sufficient conjugation to reduce the lowest triplet energy level and the host assists the guest in exciton transfer and inhibits the non-radiative transition of guest excitons. These materials exhibit good tissue penetration in bioimaging. Thanks to the characteristic of long lifetime and long wavelength emissive phosphorescence materials, the tumor imaging in living mice with a signal to background ratio value as high as 43 is successfully realized. This work provides a practical solution for the construction of organic phosphorescence materials with both long wavelengths and long lifetimes.

Extracellular vesicles (EVs) released by mesenchymal stem cells (MSCs) have exhibited regenerative capability in animal models of ischemia–reperfusion (I/R) acute kidney injury (AKI) and are considered as potential alternatives to direct MSC therapy. However, real-time in vivo imaging of MSC-EVs in renal I/R injury has yet to be established. Renal intracellular targets of MSC-EVs responsible for their regenerative effects also remain elusive. Here, we report that we real-time observed MSC-EVs specifically accumulated in the injured kidney and were taken up by renal proximal tubular epithelia cells (TECs) via DPA-SCP with aggregation-induced emission (AIE) characteristics. DPA-SCP precisely tracked the fate of MSC-EVs in a renal I/R injury mouse model for 72 h and exhibited superior spatiotemporal resolution and tracking ability to popular commercially available EV tracker PKH26. Further analysis revealed that the accumulated MSC-EVs stimulated mitochondrial antioxidant defense and ATP production via activating the Keap1-Nrf2 signaling pathway, which protected TECs against oxidative insult by reducing mitochondrial fragmentation, normalizing mitochondrial membrane potential, and increasing mitochondrial DNA copy number. Increased microRNA-200a-3p expression in renal TECs induced by MSC-EVs was identified as a regulatory mechanism contributing to the protective actions on mitochondria as well as stimulating the renal signal transduction pathways. In conclusion, MSC-EVs accumulated in the renal tubules during renal I/R injury and promoted the recovery of kidney function via activating the Keap1-Nrf2 signaling pathway and enhancing mitochondrial function of TECs. DPA-SCP with AIE characteristics allows noninvasive and precise in vivo visualization of MSC-EVs in kidney repair.