Large‐area 2D cocrystals with strong near‐infrared (NIR) absorption have been designed and prepared. Driven by the intermolecular charge‐transfer (CT) interactions, zinc tetraphenylporphyrin (donor) and C60 (acceptor) self‐assemble into a NIR cocrystal with absorption wavelength up to 1080 nm. By tailoring the growth solvents and processes, the cocrystal morphologies can be tuned from 1D nanowires, 2D nanosheets to large‐area 2D cocrystal films with length reaching several millimeters. Owing to the highly ordered donor–acceptor arrangement, the CT absorption in the 2D cocrystals is enhanced and is comparable to singlet absorption. The uniform 2D cocrystals, with enhanced CT absorption in the NIR region, displays a high responsivity of 2424 mA W−1 to NIR light and a fast response time of 0.6 s. The excellent device performance is attributed to the generation of long‐lived free charge carriers as revealed by transient absorption spectroscopy and optimization of device configuration.

Luminescence originated from singlet (S1) and triplet (T1) states is categorized as fluorescence and phosphorescence, respectively. Modulation of fluorescence and phosphorescence pathways plays a central role in developing organic luminescent materials, but remains difficult because of the lack of control ways. Here, luminescence of cocrystals of 1,7‐phenanthroline (PR) and 1,4‐diiodotetrafluorobenzene (DITFB) can be switched by adjusting their stoichiometry, from bluish fluorescence for 1:0 pure PR crystal (P1D0) to yellowish phosphorescence for 1:1 PR:DITFB cocrystal (P1D1). More importantly, 2:1 PR:DITFB cocrystal (P2D1) is found to exhibit dual fluorescence and phosphorescence simultaneously, thus giving rise to white‐light emission. Experimental and time‐dependent density‐function‐theory results reveal that although the S1 and T1 energies keep invariable, high‐lying Tn states introduced in cocrystals decreases the S1–Tn energy gap, meanwhile multiple intermolecular halogen bonding enhances the spin‐orbital coupling. As a result, the S1 → Tn intersystem crossing rate (kISC) is accelerated by 2 orders of magnitude, making kISC comparable and faster than the fluorescence decay rate kFl for P1D0 (fluorescence), P2D1 (dual emissions), and P1D1 (phosphorescence), respectively. The results provide not only a quantum‐mechanical understanding but also a novel strategy to modulate the excited‐state dynamics toward fluorescence and/or phosphorescence emissions for luminescent materials.

Conventional near-infrared (NIR) luminescent probes, such as DsRed and Cy5, utilize spontaneous emission (SE) signals, which are broad (fwhm >50 nm) and often have low quantum yield. Herein, we developed smart NIR intracellular whispering-gallery mode (WGM) microlaser probes made by organic microspheres of (E)-3-(4-(diptolylamino)phenyl)-1-(1-hydroxynaphthalen-2-yl)prop-2-en-1-one (DPHP) coated with a silica shell. The overall small diameter ( D, adjustable between 2 and 10 μm) and the biocompatible silica shell ensure our core-shell microspheres (CSmSPs) to be engulfed in cells as a microlaser operating around 720 nm with a low threshold of 0.78 μJ/cm. Considering that WGM mode spacing depending strongly on its size, it will be possible to distinguish millions of individual macrophages through well-defined WGM lasing peaks (fwhm ≤2 nm) of CSmSPs of different sizes. Furthermore, we monitored the transformation of normal macrophages to foamy ones by encoding them with our NIR CSmSPs microlaser probes, which deliver constant WGM lasing signals with a spectral fluctuation <0.02 nm and excellent stability.

Synthetic routes for heteroatom‐containing polycyclic aromatic hydrocarbons (H‐PAHs) with alkyl and aryl substitution are demonstrated. Three H‐PAHs, including heteroatom‐containing rubicenes (H‐rubicenes), angular‐benzothiophenes (ABTs), and indenothiophene (IDTs) were successfully synthesized by two key steps, including polysubstituted olefin formation and cyclization. Specifically, ABT and H‐rubicenes were comprehensively investigated by single‐crystal X‐ray diffraction, NMR spectroscopy, UV‐vis absorption, cyclic voltammetry, transient absorption, and single‐crystal OFET measurements.