- Effect of mono alkoxy-carboxylate-functionalized benzothiadiazole-based donor polymers for non-fullerene solar cells
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Structural modification of benzo[c]-1,2,5-thiadiazole (BT) has been proved to be the prominent way to fine-tune the frontier energy levels and the intermolecular and intramolecular interactions in organic conjugated materials. In this study, a new acceptor unit, alkyl benzo[c][1,2,5]thiadiazole-5-carboxylate (BT-Est), was designed and synthesized by drafting mono alkoxy-carboxylate substituent on 5-position of BT core. Its compatibility in the conjugated system was investigated by co-polymerizing BT-Est with well-known benzo[1,2-b:4,5-b’]dithiophene monomers containing either 2-(2-ethylhexyl)thienyl or 2-((2-ethylhexyl)thio)thienyl side chains to form two new polymers, P1 and P2, respectively. The BT-Est yielded polymers with good solubility, medium bandgap (～1.71 eV), and deep highest occupied molecular orbital energy levels (?5.48 to ?5.54 eV). Among the polymers, P1 exhibited broader absorption, compact molecular packing, high charge carrier mobility, and effective exciton dissociation, despite of the torsion angle caused by the free rotation of the carboxylate group in the polymer backbone. Consequently, the best power-conversion efficiency of 6.9%, with a JSC of 14.6 mA cm?2, VOC of 0.9 V, and FF of 52.5% were obtained for P1-based devices with the well-known non-fullerene acceptor ITIC. We systematically expounded the structure-property relationship of the BT-Est polymers using diverse characterization methods. Our results demonstrated that the mono carboxylate-substitution on the BT core can be used as the alternate strategy to modulate the optoelectronic properties and control the aggregation in the conjugated polymers. Thus, BT-Est has the potential to produce new donor–acceptor conjugated polymers and small molecules for application in organic electronics.
- Kini, Gururaj P.,Choi, Jun Young,Jeon, Sung Jae,Suh, Il Soon,Moon, Doo Kyung
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- Organic NIR-II dyes with ultralong circulation persistence for image-guided delivery and therapy
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Nanocarriers hold great promise for the controlled release of therapeutic payloads to target organs/tissues and extended duration of anticancer agents in the bloodstream. However, limited data on their in vivo pharmacokinetics and delivery process hamper clinical applications. Here we report a series of micellar nanocarriers self-assembled from new-generation thiophenthiadiazole (TTD)-based NIR-II fluorophores HLAnP (n = 1–4) for simultaneous bioimaging and drug delivery. The NIR-II HLA4P nanocarrier displays exceptional non-fouling performance, minimal immunogenicity, ultralong blood half-life, and high tumor accumulation even with different administration routes. When used as a drug carrier, HLA4P with encapsulated doxorubicin (DOX) realized accurate tumor targeting and continuous real-time in vivo NIR-II tracking of drug delivery and therapy, showing a sustained release rate, improved therapeutic effect, and diminished cardiotoxicity as compared to free DOX. This study provides a new perspective on the design of dual-functional NIR-II fluorophores for diagnostic and therapeutic applications.
- Li, Yang,Gao, Jianfeng,Wang, Shuping,Li, Shijun,Hou, Xiaowen,Pan, Yanna,Gao, Jialu,Qiao, Xue,Tian, Zhiquan,Chen, Deliang,Deng, Hai,Deng, Zixin,Hong, Xuechuan,Xiao, Yuling
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p. 157 - 169
(2022/01/14)
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- Low band gap conjugated small molecules containing benzobisthiadiazole and thienothiadiazole central units: Synthesis and application for bulk heterojunction solar cells
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Two novel conjugated low band gap small molecules (SMs), M1 and M2, containing benzobisthiadiazole and thienothiadiazole central units, respectively, were synthesized. Both SMs carried terminal cyanovinylene 4-nitrophenyl at both sides which were connected to the central unit with a thiophene ring. The long-wavelength absorption band was located at 591-643 nm and the optical band gap was 1.62-1.63 eV, which is lower than that of P3HT. These two SMs were investigated as electron donor materials along with PCBM or F as electron acceptors for fabrication of bulk heterojunction (BHJ) organic photovoltaic devices. F is a modified PCBM which has been previously synthesized and used as an electron acceptor for poly(3-hexylthiophene) (P3HT). The power conversion efficiency (PCE) for M1:PCBM, M1:F, M2:PCBM and M2:F was 1.05%, 2.02%, 1.23% and 2.72%, respectively. The higher PCE for the devices with M2 as the electron donor has been related to the improved hole mobility for M2. However, the improved PCE for the devices with F as the electron acceptor has been attributed to the more intense absorption of F in the visible region than that of PCBM and also to the higher open circuit voltage resulting from the higher LUMO level of F. We have also fabricated devices with M2:F cast film from mixed solvents. The PCE for the BHJ devices with the as cast and thermally annealed M2:F (mixed solvents) is 3.34% and 3.65%, respectively.
- Mikroyannidis,Tsagkournos,Sharma,Vijay,Sharma
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p. 4679 - 4688
(2011/10/13)
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- Photochemical stability of π-conjugated polymers for polymer solar cells: A rule of thumb
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A comparative photochemical stability study of a wide range of π-conjugated polymers relevant to polymer solar cells is presented. The behavior of each material has been investigated under simulated sunlight (1 sun, 1000 W m-2, AM 1.5G) and ambient atmosphere. Degradation was monitored during ageing combining UV-visible and infrared spectroscopies. From the comparison of the collected data, the influence of the polymer chemical structure on its stability has been discussed. General rules relative to the polymer structure-stability relationship are proposed.
- Manceau, Matthieu,Bundgaard, Eva,Carle, Jon E.,Hagemann, Ole,Helgesen, Martin,Sondergaard, Roar,Jorgensen, Mikkel,Krebs, Frederik C.
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supporting information; experimental part
p. 4132 - 4141
(2011/10/08)
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- Low-band gap copolymers containing thienothiadiazole units: Synthesis, optical, and electrochemical properties
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Novel low-band gap alternating copolymers consisting of 9,9-bis(2-ethylhexyl)fluorene and 4,6-di(2-thienyl)thieno[3,4-c][1,2,5] thiadiazole and its 3,3″-dialkyl derivatives were synthesized by Suzuki copolymerization reaction, and their photophysical and electrochemical properties were studied. The copolymers possess small optical band gap 1.3-1.4 eV. The absorption covers the whole visible spectral region. The long-wavelength absorption maxima in thin films located at approximately 750-785 nm are significantly red shifted compared with those in solution, indicating strong intermolecular interactions. The introduction of alkyl chains to the thiophene units increases the molecular weights of soluble fractions and solubility of the final copolymers, leading to the improved processability of thin films. Polymer solutions exhibited solvatochromism and thermochromism, which is strongly supported by the involvement of the alkyl chains. The copolymers exhibited ambipolar redox properties and reversible electrochromic behavior. The electronic properties are influenced only slightly by alkyl substituents.
- Kminek, Ivan,Vyprachticky, Drahomir,Kriz, Jaroslav,Dybal, Jiri,Cimrova, Vera
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p. 2743 - 2756
(2011/03/19)
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