As a critical component for photodynamic therapy toward cancer treatment, photosensitizers require high photoinduced reactive oxygen species generation efficiency, good biocompatibility, and high phototoxicity. Herein, a series of donor−acceptor conjugated polymers containing dibenzothiophene-S,Sdioxide derivatives are designed and synthesized, which can be used as effective photosensitizers. The resulting copolymer PTA5 shows strong green light emission with high photoluminescence quantum yields owing to the intercrossed excited state of local existed and charge transfer states. The PTA5 nanoparticles can be fabricated by encapsulation with a biocompatible polymer matrix. Upon excitation at 800 nm, these nanoparticles present a relatively large two-photon absorption cross section of 3.29 × 10 6 GM. These nanoparticles also exhibit good photostability in water and thus can be utilized for bioimaging. The tissuepenetrating depths of up to 170 μm for hepatic vessels and 380 μm for blood vessels of mouse ear were achieved using PTA5 nanoparticles. Furthermore, PTA5 nanoparticles show impressive reactive oxygen species generation capability under the irradiation of a white light source. This can be attributed to the effective intersystem crossing between high-level excited state. Upon irradiation with white light (400−700 nm) at 50 mW cm −2 for 5 min every other day, the tumor growth can be effectively suppressed in the presence of PTA5 nanoparticles. These findings demonstrate that PTA5 nanoparticles can be used as a photosensitizer for photodynamic therapy.

In order to obtain high-performance all-small-molecule organic solar cells (ASM-OSCs), it is crucial to exploit the available strategy for molecular design and to further understand key structure–property relationship that can rationally control the blend nanomorphology and influence the physical process. In this work, we design two small molecule donors FBD-S1 and TBD-S2 with identical electron-withdrawing units but various asymmetric central cores, which exhibit differing phase separation in Y6-based blend films. It is found that TBD-S2 with increased phase separation between donor and acceptor can lead to more favorable interpenetrating networks, effective exciton dissociation, and enhanced and more balanced charge transport. Importantly, a remarkable PCE of 13.1% is obtained for TBD-S2:Y6 based ASM-OSCs, which is an attractive photovoltaic performance for ASM-OSCs. This result demonstrates that the central core modification at the atomic level for small molecule donors can delicately control the phase separation and optimize photophysical processes, and refines device performance, which facilitate development in the ASM-OSC research field.

Blue light-emitting polymers were synthesized via introducing a 9,9-dioctylfluorene bis[2,3-b;6,7-b]benzo-[d]thiophene-S,S-dioxide (FBTO) unit into the polyfluorene or polycarbazole backbone.

ARTICLE This journal isA series of novel linearly-fused polycyclic aromatic compounds, N-(2-decyltetradecyl)carbazole bis [2,3b;6,7-b]benzo [d] thiophene-S,S-dioxide (CzBTO) and 9,9-dioctylfluorene bis[2,3-b;6,7b]benzo[d]thiophene-S,S-dioxide (FBTO), incorporating with S,S-dioxide benzothiophene unit were efficiently synthetized and detailedly characterized. The key step of preparing CzBTO and FBTO was related to the triflic acid induced intramolecular electrophilic cyclizing reaction where the corresponding methyl sulfoxides in activated aromatic building blocks may enable the regioselective ring cyclization. From the photoluminescence (PL) spectra, the CzBTO and FBTO showed very deep blue emission with the emission peaks at 426 and 407 nm, respectively. Through the photoluminescence quantum yield (PLQY) characterization, the FBTO gave a high PLQY value of 77% in tetrahydrofuran solution. The DFT and electrochemical studies showed that the CzBTO and FBTO had large band gaps and very low highest occupied molecular orbital (HOMO) energy levels, which indicated that these two compounds existed the high stability both thermally and optically. From the electrochemical measurement, the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels were -6.04, -6.20 and -2.74, -2.80 eV, with the band gaps of 3.3 and 3.4 eV for CzBTO and FBTO, respectively. ARTICLEThis journal is