Influence of bifurcation position and length of side chains on the structure of isoindigo-based conjugated polymer thin films

We chose a series of isoindigo-based conjugated polymer(ⅡDDT,ⅡDDT-C3 and ⅡDDT-C4) with different length of side chains and bifurcation positions to investigate the relationship between the degree of alignment and the length of side chains and bifurcation positions.We found that the dichroic ratio was increased from 2.37 to 5.23 when the side chain was longer and the bifurcation position was away from the backbone.The π-π stacking distance was decreased from 3.67 A to 3.61 A when the bifurcation position was away from the backbone because of its smaller hindrance and the d-spacing of the(100)was increased from 20.06 A to 25.21 A when the side chain was longer.All the polymers were adopted an edge-on orientation with the backbone paralleled with the long axis of fibers.The weak interaction of side-chain in ⅡDDT-C4 was beneficial for the molecules being rearranged in parallel during the contact line receding and the strong n-n interaction could accelerate the interchain assembly of the parallel molecules through π-π interaction to form aligned fibers.     

Enhancing the healing ability and charge transport thermal stability of a diketopyrrolopyrrole based conjugated polymer by incorporating coumarin groups in the side chains

In this paper, we present a new design strategy for healable polymeric semiconductors, which are demanding for the future flexible electronics, by incorporating coumarin groups in the polymer side chains. The selection of coumarin groups is based on the fact that photo-dimerization can occur to coumarins upon UV light irradiation, thus side chains of conjugated polymers with coumarins can be cross-linked. The photo-crosslinking of side chains has negligible effect on the thin film morphology and interchain packing order for the DPP-based conjugated polymer PDPP4T-DCM with coumarins in the side chains. However, the photo-crosslinking can facilitate the repair of the mechanically damaged thin film of PDPP4T-DCM and the recovery of the semiconducting properties. Additionally, the photo-crosslinking due to the coumarins in the side chains can lock thin film morphology and thus improve the thermal stability of charge transport.     

Preparation of new π‐conjugated polypyrroles by organometallic polycondensations. Synthesis of N‐BOC (t‐butoxycarbonyl) and N‐phenylethynyl polymers,thermal deprotection of the BOC Group,and packing structure of the N‐phenylethynyl polymer

New π–conjugated polypyrroles such as poly(3‐heptyl‐N‐(t‐butoxycarbonyl)pyrrole‐2,5‐diyl), PPr(3‐Hep; N‐BOC) , and poly(N‐(phenylethynyl)pyrrole‐2,5‐diyl‐alt‐thiophene‐2,5‐diyl), Copoly‐2 , were prepared by organometallic polycondensations using the corresponding 2.5‐dihalopyrroles as the starting materials. Deprotection of the BOC group of PPr(3‐Hep; N‐BOC) proceeded at 185 °C to give poly(3‐heptylpyrrole). XRD (X‐ray diffraction) data of Copoly‐2 indicated that Copoly‐2 assumed a stacked structure in the solid. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6223–6232, 2005     

Synthesis of π‐conjugated polymer containing both thiophene and phosphole sulfide in the main chain by simultaneous post‐element transformation of organotitanium polymer

The synthesis and unique optoelectronic features of a π‐conjugated polymer containing both thiophene and 1‐phenylphosphole sulfide units (multiple heteroles) in the main chain by the post‐element transformation of a regioregular organometallic polymer possessing titanacyclopentadiene‐2,5‐diyl unit are described. The π‐conjugated polymer containing multiple heteroles was obtained in 73% yield by the simultaneous reaction of the organotitanium polymer with sulfur monochloride and dichlorophenylphosphine (0.6 equiv each), whose number‐average molecular weight (M_n) and the molecular‐weight distribution (M_w/M_n) were estimated to be 11,000 and 3.4, respectively, by the size exclusion chromatography (SEC). The π‐conjugated polymer thus obtained was found to have the high HOMO and the low LUMO energy levels due to the electron‐rich thiophene and electron‐deficient phosphole sulfide units, respectively, as supported by its cyclic voltammetry (CV) analysis. Compared to a mixture of a polymer containing sole thiophene‐unit and that containing sole phosphole sulfide units, the π‐conjugated polymer‐containing multiple heteroles proved to exhibit interesting optical properties. For example, a specific emission peak was observed at 608 nm in the photoluminescence spectrum, which was not observed in the case of the thiophene‐containing polymer, the phosphole‐containing polymer, and their mixture. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2519–2525     

Tuning the electronic properties of conjugated polymer by tethering low‐bandgap rhenium(I) complex on the main chain

Low‐bandgap rhenium(I) complex with absorption onset at 795 nm in solution was tethered onto π‐conjugated polymer. The conjugated copolymer provides solution processability of the metallopolymer, and the pendant allows the low energy‐absorbing Re(I) complex units to be evenly distributed on the thin film. The copolymer tethered with low‐bandgap rhenium complex was synthesized by Suzuki cross‐coupling reaction. The metal‐free polymer ( poly‐1 ) tethered with functionalized intramolecular charge transfer dye, 2‐phenyl‐3‐pyridin‐2‐yl‐5,7‐di‐2‐thienylthieno[3,4‐b]pyrazine, exhibited high molecular weight, good film‐forming properties, and excellent solution processability. The pendants of the conjugated polymer possess donor–acceptor characters and broaden the absorption band. These pendants can function as bidentate ligands for metal chelation. The solubilizing groups on the monomers provide good solubility to the polymer even with high content of metal chelation. Upon the complexation with rhenium(I) pentacarbonyl chloride, the absorption spectrum of the resulting metallopolymer was further extended toward the near‐infrared region. Photovoltaic performances based on this metallopolymer have been studied. The design approach of these metallopolymers provides synthetic feasibility for coordinating wide range of metal ions on the pendant, and the resulting low‐bandgap polymer can be a potential candidate for light harvesting material in solar cell applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2311–2319, 2010     

Simultaneous imaging of the structure and fluorescence of a supramolecular nanostructure formed by the coupling of π‐conjugated polymer chains in the intermolecular interaction

We fabricated a micrometer‐long supramolecular chain in which π‐conjugated polyrotaxane was coupled. A new experimental setup was designed and constructed, and the simultaneous direct imaging of the structure and fluorescent function was achieved. Furthermore, we identified the formation of a polymer intertwined network and observed novel fluorescence due to a long‐range interaction via this intertwined network over a distance of 5 μm or more without quenching over 15 min in the near field. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 801–809, 2006     

Tuning the frontier molecular orbital energy levels of n‐type conjugated copolymers by using angular‐shaped naphthalene tetracarboxylic diimides,and their use in all‐polymer solar cells with high open‐circuit voltages

An angular‐shaped naphthalene tetracarboxylic diimide (NDI) was designed and synthesized as a new building block for n‐type conjugated polymers to tune their energy levels. Three n‐type copolymers incorporating this angular‐shaped NDI as the acceptor moiety were obtained by Stille coupling reactions and had number average molecular weights of 18.7–73.0 kDa. All‐polymer bulk‐heterojunction solar cells made from blends of these polymers with poly(3‐hexylthiophene) gave a power conversion efficiency up to 0.32% and exhibited an open‐circuit voltage (V_oc) up to 0.94 V due to their relative high‐lying lowest unoccupied molecular orbital energy levels. The high V_oc of 0.94 V is higher than that of solar cells based on linear‐shaped NDI‐containing polymers (<0.6 V). The results indicate that the angular‐shaped NDI is a promising building block for constructing nonfullerene polymer acceptors for solar cells with high open‐circuit voltages. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013