New, biocompatible materials with favorable antibacterial activity are highly desirable. In this work, we develop a unique conjugated polymer featuring aggregation‐induced emission (AIE) for reliable bacterial eradication. Thanks to the AIE and donor‐π‐acceptor structure, this polymer shows a high reactive oxygen species (ROS)‐generation ability compared to a low‐mass model compound and the common photosensitizer Chlorin E6. Moreover, the selective binding of pathogenic microorganisms over mammalian cells was found, demonstrating its biocompatibility. The effective growth inhibition of bacteria upon polymer treatment under light irradiation was validated in vitro and in vivo. Notably, the recovery from infection after treatment with our polymer is faster than that with cefalotin. Thus, this polymer holds great promise in fighting against bacteria‐related infections in practical applications.

The exploration of biocompatible materials with circularly polarized luminescence (CPL) activity is becoming an attractive topic due to the great potential application in biosensing and bioimaging. Here, we describe a strategy to fabricate new CPL-active biomaterials using achiral carbazole-based biscyanine fluorophores coassembled with chiral deoxyribonucleic acid (DNA) molecules. This cyanine molecule has been shown to behave as a DNA detecting probe, featuring strong fluorescent emission induced by restriction of intramolecular rotation (RIR). When the achiral cyanine molecules are bound to the minor groove of DNA via electrostatic attraction in aqueous solution, the chirality of the DNA molecules can be transferred to the confined RIR cyanine dyes, triggering a remarkable circularly polarized luminescent emission. The chirality of the CPL signal can be regulated by the structures of the DNA templates. Stimuli-responsive CPL activates were observed from DNA–cyanine complexes. We further verified this strategy on different DNA-based nanomaterials, including DNA origami nanostructure. Our design presents a new avenue to fabricate compatible CPL materials.

Actualizing full singlet exciton yield via a reverse intersystem crossing from the high‐lying triplet state to singlet state, namely, “hot exciton” mechanism, holds great potential for high‐performance fluorescent organic light‐emitting diodes (OLEDs). However, incorporating comprehensive insights into the mechanism and effective molecular design strategies still remains challenging. Herein, three blue emitters (CNNPI, 2TriPE‐CNNPI, and 2CzPh‐CNNPI) with a distinct local excited (LE) state and charge‐transfer (CT) state distributions in excited states are designed and synthesized. They show prominent hybridized local and charge‐transfer (HLCT) states and aggregation‐induced emission enhancement properties. The “hot exciton” mechanism based on these emitters reveals that a balanced LE/CT distribution can simultaneously boost photoluminescence efficiency and exciton utilization. In particular, a nearly 100% exciton utilization is achieved in the electroluminescence (EL) process of 2CzPh‐CNNPI. Moreover, employing 2CzPh‐CNNPI as the emitter, emissive dopant, and sensitizing host, respectively, the EL performances of the corresponding nondoped pure‐blue, doped deep‐blue, and HLCT‐sensitized fluorescent OLEDs are among the most efficient OLEDs with a “hot exciton” mechanism to date. These results could shed light on the design principles for “hot exciton” materials and inspire the development of next‐generation high‐performance OLEDs.