%0 Journal Article
%T Polaron engineering promotes NIR-II absorption of carbon quantum dots for bioimaging and cancer therapy.
%A Zhang T
%A Wang B
%A Cheng Q
%A Wang Q
%A Zhou Q
%A Li L
%A Qu S
%A Sun H
%A Deng C
%A Tang Z
%J Sci Adv
%V 10
%N 27
%D 2024 Jul 5
%M 38968361
%F 14.957
%R 10.1126/sciadv.adn7896
%X Recent years have witnessed a surge of interest in tuning the optical properties of organic semiconductors for diverse applications. However, achieving control over the optical bandgap in the second near-infrared (NIR-II) window has remained a major challenge. To address this, here we report a polaron engineering strategy that introduces diverse defects into carbon quantum dots (CQDs). These defects induce lattice distortions resulting in the formation of polarons, which can absorb the near-field scattered light. Furthermore, the formed polarons in N-related vacancies can generate thermal energy through the coupling of lattice vibrations, while the portion associated with O-related defects can return to the ground state in the form of NIR-II fluorescence. On the basis of this optical absorption model, these CQDs have been successfully applied to NIR-II fluorescence imaging and photothermal therapy. This discovery could open a promising route for the polarons of organic semiconductor materials as NIR-II absorbers in nanomedical applications.