We developed a biodegradable photothermal therapeutic (PTT) agent, π-conjugated oligomer nanoparticles (F8-PEG NPs), for highly efficient cancer theranostics. By exploiting an oligomer with excellent near-infrared (NIR) absorption, the nanoparticles show a high photothermal conversion efficiency (PCE) up to 82%, surpassing those of reported inorganic and organic PTT agents. In addition, the oligomer nanoparticles show excellent photostability and good biodegradability. The F8-PEG NPs are also demonstrated to have excellent biosafety and PTT efficacy both in vitro and in vivo. This contribution not only proposes a promising oligomer-based PTT agent but also provides insight into developing highly efficient nanomaterials for cancer theranostics.

Extensive recent efforts have been put on the design of high‐performance organic near‐infrared (NIR) photothermal agents (PTAs), especially over NIR‐II bio‐window (1000–1350 nm). So far, the development is mainly limited by the rarity of molecules with good NIR‐II response. Here, we report organic nanoparticles of intermolecular charge‐transfer complexes (CTCs) with easily programmable optical absorption. By employing different common donor and acceptor molecules to form CTC nanoparticles (CT NPs), absorption peaks of CT NPs can be controllably tuned from the NIR‐I to NIR‐II region. Notably, CT NPs formed with perylene and TCNQ have a considerably red‐shifted absorption peak at 1040 nm and achieves a good photothermal conversion efficiency of 42 % under 1064 nm excitation. These nanoparticles were used for antibacterial application with effective activity towards both Gram‐negative and Gram‐positive bacteria. This work opens a new avenue into the development of efficient PTAs.

Solar water evaporation has been considered as a promising technique to harvest solar energy for practicable water evaporation. While different classes of materials have been exploited as solar absorbers, to date there is no report on using small organic molecules because of their narrow optical absorption spectra. We show here for the first time that full solar spectrum absorption can be conveniently achieved with commercially available small molecules via the formation of charge-transfer complex (CTC) cocrystals between the suitable donor and acceptor molecules. We demonstrate that a porous polymer scaffold loaded with suitable CTC cocrystal can show efficient full solar photothermal conversion leading to a high water evaporation rate of 1.67 kg m–2 h–1 via 90.3% solar conversion under 1 Sun, with practical multiple wastewater purification. This is the first report of a high-performance solar absorber using small organic molecules, suggesting CTC is a promising new class of solar absorbers deserving more attention.

A plasmonic solar absorber, featuring broadband light harvesting by manipulating the structural anisotropy at the single nanoparticle level, enables absorption over the entire solar spectrum.

Effective multimodality phototheranostics under deep-penetration laser excitation is highly desired for tumor medicine, which is still at a deadlock due to lack of versatile photosensitizers with absorption located in the long-wavelength region. Herein, we demonstrate a stable organic photosensitizer nanoparticle based on molecular engineering of benzo[c]thiophene (BT)-based photoactivated molecules with strong wavelength-tunable absorption in the near-infrared region. Via molecular design, the absorption and singlet oxygen generation of BT molecules would be reliably tuned. Importantly, the nanoparticles with a red-shifted absorption peak of 843 nm not only show over 10-fold reactive oxygen species yield compared with indocyanine green but also demonstrate a notable photothermal effect and photoacoustic signal upon 808 nm excitation. The in vitro and in vivo experiments substantiate good multimodal anticancer efficacy and imaging performance of BT theranostics. This work provides an organic photosensitizer nanoparticle with long-wavelength excitation and high photoenergy conversion efficiency for multimodality phototherapy.