设计并合成了一种交叉共轭的(cross-conjugated)缺电子型聚合物单体——二溴代噻吩[2,3-b]并噻吩-吡咯[3,4-c]并吡咯(DPPTTZ)二酮,并将其分别与噻吩(T)、硒吩(Se)和N-甲基吡咯(Py)的双锡试剂进行共聚反应,获得了一类新的供体-受体(D-A)型共轭聚合物光电材料.这类材料分子的最高占有轨道(HOMO)能级较低,因此其光电器件具有较高的开路电压(Voc),稳定性好.此外,它们在紫外-可见光区有较宽的吸收,最大吸收位于波长620 nm附近;能带隙(band gap)小,分别为1.86 e V(p DPPTTZ-T)、1.83 e V(p DPPTTZ-Se)和1.85 e V(p DPPTTZ-Py).器件初步测试结果表明,上述聚合物与PC71BM组成的本体异质结聚合物太阳能电池Voc在0.68~0.81 V之间,能量转化效率(PCE)最高达3.05%(p DPPTTZ-T). 相似文献
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. 相似文献
The solution-processability of conjugated polymers in organic solvents has classically been achieved by modulating the size and branching of alkyl substituents appended to the backbone. However, these substituents impact structural order and charge transport properties in thin-film devices. As a result, a trade-off must be found between material solubility and insulating alkyl content. It was recently shown that the substitution of furan for thiophene in the backbone of the polymer PDPP2FT significantly improves polymer solubility, allowing for the use of shorter branched side chains while maintaining high device efficiency. In this report, we use PDPP2FT to demonstrate that linear alkyl side chains can be used to promote thin-film nanostructural order. In particular, linear side chains are shown to shorten π-π stacking distances between backbones and increase the correlation lengths of both π-π stacking and lamellar spacing, leading to a substantial increase in the efficiency of bulk heterojunction solar cells. 相似文献
Few semiconducting polymers are known that possess more than one semi-crystalline structure. Guidelines for rationalizing or creating polymorphism in these materials do not exist. Two different semi-crystalline polymorphs, β1 and β2, and an amorphous α phase have recently been identified for alternating diketopyrrolopyrrole-quaterthiophene copolymers (PDPP4T). The polymorphs differ structurally by the π–π stacking distance, and electronically by the optical bandgap and charge carrier mobility. Here we investigate the corresponding terthiophene (PDPP3T) derivatives, to study the effect of the relative orientation of adjacent DPP units on the polymorphism. In PDPP3T, the relative orientation of DPP units alternates along the chain, while in PDPP4T it is constant. We show that the two polymorphs, β1 and β2, can also be generated for a PDPP3T polymer in solution and thin film. Interestingly, compared to PDPP4T, more solvents can induce the two distinct semi-crystalline polymorphs for PDPP3T via a β1 → α → β2 polymorphic transition. 相似文献
A poly(2-(2-bromopropionyloxy)ethyl methacrylate) (PBPEM) was used as macroinitiator in the synthesis of molecular brushes with poly(4-vinylpyridine) side chains, (P(BPEM-g-4VP). Atom transfer radical polymerization (ATRP) was employed as the polymerization technique. The polymerizations were carried out in DMF at 30 °C using a copper-chloride-based ATRP catalyst, which converted all the dormant polymer chain ends to alkyl chloride groups, thus minimizing branching and crosslinking, which occurred when a copper bromide-based catalyst was employed. Tris(2-pyridylmethyl)amine was selected as the ligand due to the high activity of its CuI complex in ATRP as well as its strong binding to both CuI and CuII, which prevented competitive complexation of the monomer or polymer to the metal center. In order to prevent crosslinking via radical coupling, the monomer conversion was kept low (under 3%) and the alkyl chloride end groups of P4VP side chains were converted to alkoxyamines upon activation followed by a reaction with TEMPO radical. Dynamic light scattering measurements showed the hydrodynamic diameter (DH) of the brushes was pH-dependent. Aggregation of single P(BPEM-g-4VP) brushes in water was very pronounced at high pH values but was observed even when the amount of added HCl was enough to completely protonate the pyridine units (DH = 278 nm). 相似文献
A new electroactive polymer 1 with alternating NDI (naphthalene diimide) moieties and fluorinated alkyl chains was prepared and characterized. Gels of polymer 1 were formed in several solvents. Interestingly, gels of polymer 1 exhibited responsiveness toward N2H4, F? and CN?. Absorption and ESR spectroscopic studies revealed that such responsiveness is owing to the reduction of NDI moieties into the respective NDI.?. In addition, thin films of polymer 1 were easily prepared with spin‐coating technique and the electrical conductivity of thin films reached 52.4 S/m after exposure to N2H4 vapor. 相似文献
Photoresists are essential for the fabrication of flexible electronics through all-photolithographic processes. Single component semiconducting photoresist exhibits both semiconducting and photo-patterning properties, and as a result, the device fabrication process can be simplified. However, the design of semiconducting polymeric photoresist with ambipolar semiconducting property remains challenging. In this paper, we report a single component semiconducting photoresist (PFDPPF4T-N3) by incorporating azide groups and noncovalent conformation locks into the side alkyl chains and conjugated backbones of a diketopyrrolopyrrole-based conjugated polymer, respectively. The results reveal that PFDPP4FT-N3 exhibits ambipolar semiconducting property with hole and electron mobilities up to 1.12 and 1.17 cm2 V?1 s?1, respectively. Moreover, field effect transistors with the individual photo-patterned thin films of PFDPPF4T-N3 also show ambipolar semiconducting behavior with hole and electron mobilities up to 0.66 and 0.80 cm2 V?1 s?1, respectively. These results offer a simple yet effective design strategy for high-performance single component semiconducting photoresists, which hold great potential for flexible electronics processed by all photolithography.
Spatial distance is an important factor in controlling the functional interactions between molecular units in a conjugate; therefore, the bridging unit has been closely examined. Here, we examined the effect of the flexibility of bridging alkyl chains on the proximity of stacked porphyrin and phthalocyanine conjugated with a fourfold rotaxane linkage. We found that closely stacking two π systems requires bridging alkyl chains above a certain length, and the shorter bridges hinder stacking because of their lower flexibility. The stacking distance between porphyrin and phthalocyanine in the conjugate with decyl (C10) chains was estimated to be 4.03 Å and showed a unique physical character arising from short-distance interactions. The longer alkyl chains minimized steric restriction inside the fourfold rotaxane and allowed efficient communication between the porphyrin and phthalocyanine units. This is due to the flexibility of the side chains. 相似文献
New arylacetylene‐substituted naphthalene diimides (NDIs) 1–6 , with both light‐emitting and semiconducting functions, are reported. Among them, the crystal structure of 1 was determined. On the basis of their reduction potentials and thin‐film absorption spectra, the HOMO/LUMO energies of these modified NDIs were estimated. The results reveal that their HOMO/LUMO energies are slightly affected by the flanking aryl groups. The emission colors of these NDIs vary from green to red, and interestingly, they show aggregation‐induced emission enhancement behavior with fluorescence quantum yields reaching 9.86 % in the solid state. Microrods of 1 , 3 , and 5 show typical optical wave‐guiding behavior with relatively low optical‐loss coefficients. Organic field‐effect transistors with thin films of these NDIs were fabricated with conventional techniques. The results indicate that thin films of 2 , 4 , and 6 , with long and branched alkyl chains, show air‐stable n‐type semiconducting properties with electron mobilities of up to 0.035 cm2 V?1 s?1 after thermal annealing, whereas 1 , 3 , and 5 , with short alkyl chains, behave as n‐type semiconductors under a nitrogen atmosphere with electron mobilities of up to 0.075 cm2 V?1 s?1 after thermal annealing. 相似文献