Enhanced Photothermal Therapy under Low‐Power Near‐Infrared Irradiation Enabled by a Si‐Cyclopentadithiophene‐Based Organic Molecule

Due to the inadequate photothermal conversion efficiency (PCE), most photothermal agents (PTAs) have to be used under high-power near-infrared (NIR) irradiation, which significantly exceeds medical safety standards, for achieving effective photothermal therapy (PTT) in antitumor treatment. This significantly hinders practical PTT application. Herein, three acceptor-donor-acceptor(A-D-A)-type molecules are synthesized based on cyclopentadithiophene unit to develop effective PTAs. By incorporating the large-size Si atom in the A-D-A molecules, the photosensitizer displays an increased packing distance in the aggregate state, leading to a blue-shifted absorption spectrum that better matches the medial laser wavelength. Also, the Si incorporation strategy elevates the nonradiative decay rate constants (k