Fullerene‐free and processing additive‐free 8.5% efficient polymer solar cells are achieved by using a new 3,4‐ethylenedioxythiophene‐linked arylene diimide dimer with a 76° twist angle. The devices ...combine high (78–83%) external quantum efficiency with high (0.91–0.95 V) photovoltages and thus have relatively low optical bandgap energy loss.
This review focuses on the expanding role of marine collagen (MC)-based scaffolds for biomedical applications. A scaffold-a three-dimensional (3D) structure fabricated from biomaterials-is a key ...supporting element for cell attachment, growth, and maintenance in 3D cell culture and tissue engineering. The mechanical and biological properties of the scaffolds influence cell morphology, behavior, and function. MC, collagen derived from marine organisms, offers advantages over mammalian collagen due to its biocompatibility, biodegradability, easy extractability, water solubility, safety, low immunogenicity, and low production costs. In recent years, the use of MC as an increasingly valuable scaffold biomaterial has drawn considerable attention from biomedical researchers. The characteristics, isolation, physical, and biochemical properties of MC are discussed as an understanding of MC in optimizing the subsequent modification and the chemistries behind important tissue engineering applications. The latest technologies behind scaffold processing are assessed and the biomedical applications of MC and MC-based scaffolds, including tissue engineering and regeneration, wound dressing, drug delivery, and therapeutic approach for diseases, especially those associated with metabolic disturbances such as obesity and diabetes, are discussed. Despite all the challenges, MC holds great promise as a biomaterial for developing medical products and therapeutics.
All‐polymer solar cells with 4.8% power conversion efficiency are achieved via solution processing from a co‐solvent. The observed short‐circuit current density of 10.5 mA cm−2 and external quantum ...efficiency of 61.3% are also the best reported in all‐polymer solar cells so far. The results demonstrate that processing the active layer from a co‐solvent is an important strategy in achieving highly efficient all‐polymer solar cells.
Arylene linkers in a series of new tetraazabenzodifluoranthene diimide dimers enable tuning of the 3D molecular structure of nonfullerene electron acceptors, facilitating observation of dramatic ...variation of the power conversion efficiency from 2.6% to 6.4% as the twist angle between the monomeric building blocks in the dimer is varied.
7.7% Efficient All-Polymer Solar Cells Hwang, Ye-Jin; Courtright, Brett A. E.; Ferreira, Amy S. ...
Advanced materials (Weinheim),
August 19, 2015, Letnik:
27, Številka:
31
Journal Article
Recenzirano
By controlling the polymer/polymer blend self‐organization rate, all‐polymer solar cells composed of a high‐mobility, crystalline, naphthalene diimide‐selenophene copolymer acceptor and a ...benzodithiophene‐thieno3,4‐bthiophene copolymer donor are achieved with a record 7.7% power conversion efficiency and a record short‐circuit current density (18.8 mA cm−2).
The high reproducibility of the flow synthesis system enabled accurate investigation of the relationship between reaction conditions and molecular weight in Stille polycondensation of conjugated ...polymers. Here, a conjugated polymer, PTB7, was synthesized in a customized flow reactor using various catalyst and solvent combinations, and their effect on molecular weight was studied. Specifically, common palladium catalysts (Pd(PPh
3
)
4
and Pd
2
(dba)
3
) were screened in three different solvents (toluene, chlorobenzene, and
o
-xylene). A significant difference in molecular weight was observed depending on the type of solvent when using Pd
2
(dba)
3
as a catalyst. It was discovered that the solubility of both the catalyst and PTB7 in the solvent played a critical role in determining the molecular weight of the polymer. By using the Pd
2
(dba)
3
catalyst system, a high number-averaged molecular weight (
M
n
) for PTB7, ranging from 41.7 to 51.5 kDa, was achieved. This was 16 times higher than that obtained with the Pd(PPh
3
)
4
catalyst system in any solvent. However, the Pd(PPh
3
)
4
catalyst system showed high compatibility with dimethylformamide (DMF) co-solvent, and the
M
n
of PTB7 synthesized with the Pd(PPh
3
)
4
catalyst showed a significant increase, ranging from 53.9 to 58.7 kDa, while the
M
n
of PTB7 synthesized with the Pd
2
(dba)
3
catalyst decreased to 10.9- 15.0 kDa. The results can provide valuable guidance for optimizing the reaction conditions in the future synthesis of conjugated polymers in a flow reactor to achieve the desired molecular weight.
The high reproducibility of the flow synthesis system enabled accurate investigation of the relationship between reaction conditions and molecular weight in Stille polycondensation of conjugated polymers.
The lack of suitable acceptor (n-type) polymers has limited the photocurrent and efficiency of polymer/polymer bulk heterojunction (BHJ) solar cells. Here, we report an evaluation of three ...naphthalene diimide (NDI) copolymers as electron acceptors in BHJ solar cells which finds that all-polymer solar cells based on an NDI-selenophene copolymer (PNDIS-HD) acceptor and a thiazolothiazole copolymer (PSEHTT) donor exhibit a record 3.3% power conversion efficiency. The observed short circuit current density of 7.78 mA/cm2 and external quantum efficiency of 47% are also the best such photovoltaic parameters seen in all-polymer solar cells so far. This efficiency is comparable to the performance of similarly evaluated 6,6-Phenyl-C61-butyric acid methyl ester (PC60BM)/PSEHTT devices. The lamellar crystalline morphology of PNDIS-HD, leading to balanced electron and hole transport in the polymer/polymer blend solar cells accounts for its good photovoltaic properties.
Knowledge of the critical factors that determine compatibility, blend morphology, and performance of bulk heterojunction (BHJ) solar cells composed of an electron-accepting polymer and an ...electron-donating polymer remains limited. To test the idea that bulk crystallinity is such a critical factor, we have designed a series of new semiconducting naphthalene diimide (NDI)-selenophene/perylene diimide (PDI)-selenophene random copolymers, xPDI (10PDI, 30PDI, 50PDI), whose crystallinity varies with composition, and investigated them as electron acceptors in BHJ solar cells. Pairing of the reference crystalline (crystalline domain size L c = 10.22 nm) NDI-selenophene copolymer (PNDIS-HD) with crystalline (L c = 9.15 nm) benzodithiophene-thieno3,4-bthiophene copolymer (PBDTTT-CT) donor yields incompatible blends, whose BHJ solar cells have a power conversion efficiency (PCE) of 1.4%. However, pairing of the new 30PDI with optimal crystallinity (L c = 5.11 nm) as acceptor with the same PBDTTT-CT donor yields compatible blends and all-polymer solar cells with enhanced performance (PCE = 6.3%, J sc = 18.6 mA/cm2, external quantum efficiency = 91%). These photovoltaic parameters observed in 30PDI:PBDTTT-CT devices are the best so far for all-polymer solar cells, while the short-circuit current (J sc) and external quantum efficiency are even higher than reported values for 70-fullerene:PBDTTT-CT solar cells. The morphology and bulk carrier mobilities of the polymer/polymer blends varied substantially with crystallinity of the acceptor polymer component and thus with the NDI/PDI copolymer composition. These results demonstrate that the crystallinity of a polymer component and thus compatibility, blend morphology, and efficiency of polymer/polymer blend solar cells can be controlled by molecular design.
Current flow systems, used for conjugated polymer syntheses, have been limited to the use of homogeneous catalysts. Conventional homogeneous catalysts are often not ideal for mass production due to ...their poor air stability and high cost. Here, a heterogeneous palladium catalyst (Pd/C) was applied for the first time in a flow system to synthesize a conjugated copolymer, PTB7,
via
the Stille polymerization. During our initial trials, catalyst deactivation was observed during the reaction, and this led to a low number average molecular weight (
M
n
) of 8.2 kDa with a large molecular weight dispersity (
) of 3.35 even after 30 min of reaction time. With the aid of deactivation studies, we identified that catalyst deactivation occurred with the highest rate at the early reaction stream mainly due to poisoning of the catalyst by monomers and palladium leaching. By adding triphenylphosphine (TPP), as an antidote for the S poisoning, we demonstrated the successful synthesis of the conjugated polymer, PTB7, with an intermediate
M
n
of 13.6 kDa and
of 2.9 in 30 min. For achieving comparable results with batch reactions, 72 hours of reaction time and additional days of purification were required. These results were highly reproducible (2.15% errors in
M
n
between runs), and this demonstrates the great potential of combining heterogeneous catalysts and the flow synthesis system for conjugated polymer synthesis.
We report the first successful synthesis of a conjugated polymer using a heterogeneous palladium catalyst in a flow system. The resulting polymer with an
M
n
of 13.6 kDa and high reproducibility shows the great potential of this system.
Side chain engineering of an n-type polymer provides a means of maintaining solubility while increasing crystallinity and electron mobility, leading to enhanced photocurrent. Bulk heterojunction ...solar cells composed of a side chain engineered copolymer (PNDIS-30BO) as acceptor and PSEHTT as donor give 10.4 mA cm(-2) photocurrent and 4.4% efficiency.
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