Investigations of substituted benzofuran-3-carboxylates,benzo[1,2-b:4,5-b']difurans and benzo[1,2-b:4,3-b']difurans

The Michael addition of ethyl acetoacetate to benzoquinone, toluquinone, and chlorobenzo-quinone leads to formation of substituted 5-hydroxybenzofuran-3-earboxylates and linear benzo-[1,2-b:4,5-b']difurans. The previously reported structural proof for the benzodifurans obtained from chlorobenzoquinone and toluquinone, although correct in the conclusion, is shown to be invalid. Proof of the linear benzodifuran structures was obtained by comparison of the uv spectra with authentic angular benzo[1,2-b:4,3-b']difurans.     

Synthesis and characterization of benzo[1,2-b:3,4-b':5,6-b']trithiophene (BTT) oligomers

Two dimers (2 and 3), dendritic tetramer (4), hexamer (5), and decamer (6) of benzo[1,2-b:3,4-b':5,6-b']trithiophene (BTT), a potential π-core unit with C(3h) symmetry, were synthesized, characterized, and evaluated for possible use as organic semiconductors. Single crystal X-ray analyses of the dimers (2 and 3) revealed that they have planar molecular structures with dihedral angles of almost 180° between two BTT units. In accordance with the rigid and planar molecular structure, the unsubstituted dimer (2) is poorly soluble, whereas the octyl-substituted dimer (3) has improved solubility. Although the solubility of the dendritic tetramer (4) is decreased, further extended systems, i.e., the dendritic hexamer (5) and decamer (6), have solubilities better than that of 4. With increasing numbers of BTT units in the molecule, the experimentally determined energy levels of HOMO shift upward slightly and the HOMO-LUMO energy gaps become smaller, but the extent of HOMO destabilization and reduction of the HOMO-LUMO gap are not significant. Taking into account the energy levels of the frontier orbitals, 3-6 could be useful as p-channel organic semiconductors rather than n-channel. In fact, the spin-coated thin film of 3 with edge-on molecular orientation acted as an active channel of field-effect transistors that showed hole mobilities as high as 0.14 cm(2) V(-1) s(-1), indicating that the BTT core is a useful π-conjugated system for application to organic semiconductors, although 4-6 gave FET characteristics rather inferior to those of 3, owing to their amorphous nature in the thin film state.     

Synthesis, properties, and structures of benzo[1,2-b:4,5-b']bis[b]benzothiophene and benzo[1,2-b:4,5-b']bis[b]benzoselenophene

Employing two consecutive cyclization reactions, benzo[1,2-b:4,5-b']bis[b]benzochalcogenophenes, which are pi-extended heteroarenes, were efficiently synthesized. Their electronic and crystal structures were elucidated on the basis of UV-vis spectra, electrochemical measurements, and X-ray structural analyses.     

Organic dyes incorporating the benzo[1,2-b:4,5-b']dithiophene moiety for efficient dye-sensitized solar cells

A new class of organic sensitizers incorporating a benzo[1,2-b:4,5-b']dithiophene (BDT) unit as conjugated spacer has been synthesized and successfully used for dye-sensitized solar cells (DSSCs). The length of the π-conjugated spacers has a strong impact on electro-optical properties of these dyes, leading to the conversion efficiencies ranging from 4.17 to 5.68% under AM 1.5 G irradiation. This result indicates that the BDT unit is a promising candidate in organic sensitizers.     

6,12-二(三乙基硅乙炔基)二苯并苯并二噻吩的合成、表征及性能研究

合成了6,12-二(三乙基硅乙炔基)二苯并[d,d’]苯并[1,2-b;4,5-b’]二噻吩,并通过熔点测定、元素分析、核磁共振谱、质谱及X-单晶衍射分析对其进行了表征,同时对其作为有机场效应管(OFET)材料的性能进行了测试.结果表明,该材料在器件中载流子迁移率高达0.53 cm2/Vs,开关比为105.     

A novel dialkylthio benzo[1,2-b:4,5-b']dithiophene derivative for high open-circuit voltage in polymer solar cells

A new dialkylthio benzo[1,2-b:4,5-b']dithiophene (S-BDT) was designed and synthesized and the polymer S-PBDT was prepared by a Stille coupling reaction. A high open-circuit voltage (V(oc)) of up to 0.99 V was achieved in polymer solar cells with PCBM.     

A low band-gap polymer based on unsubstituted benzo[1,2-b:4,5-b']dithiophene for high performance organic photovoltaics

A low band-gap conjugated polymer, PBDTDPP, composed of unsubstituted benzo[1,2-b:4,5-b']dithiophene and diketopyrrolo[3,4-c]pyrrole was synthesized. The deep HOMO level of PBDTDPP enhances the V(OC) of a PSC up to 0.82 V and exhibits a PCE of 5.16%, while alkoxy substituted PBDTDPP-OR yields a PCE of 2.24% with a V(OC) of 0.61 V.     

Facile synthesis, structure, and properties of benzo[1,2-b:4,5-b']dichalcogenophenes

[reaction, structures: see text] A general and convenient synthesis of benzo[1,2-b:4,5-b']dichalcogenophenes including the thiophene (BDT, 1), selenophene (BDS, 2), and tellurophene (BDTe, 3) homologues is developed. Thus synthesized heterocycles are structurally characterized by single-crystal X-ray analysis, and all three homologues are isostructural with one another. They all have completely planar molecular structures packed in a herringbone arrangement. Their physicochemical properties were also elucidated by means of cyclic voltammetry (CV) and UV-vis spectra.     

Thin film organic transistors from air-stable heteroarenes: anthra[1,2-b:4,3-b':5,6-b':8,7-b']tetrathiophene derivatives

A facile synthesis of air-stable anthra[1,2-b:4,3-b':5,6-b':8,7-b']tetrathiophene derivatives 1a and 1b has been developed for applications in organic thin film transistors. Both molecules tend to self-associate through pi-pi stacking in solution and in different films. The hole mobility of 0.012 cm2 V(-1) s(-1) is obtained from 1a due to morphology changes in films from less ordered to highly ordered structures after thermal annealing. Good performance remained persistent over a period of 14 days, indicating the high stability of such transistors.     

A Near-infrared Non-fullerene Acceptor with Thienopyrrole-expanded Benzo[1,2-b:4,5-b′]dithiophene Core for Polymer Solar Cells

A near-infrared non-fullerene acceptor(NFA) BDTIC, based on thienopyrrole-expanded benzo[1,2-b:4,5-b′]dithiophene unit(heptacyclic S,N-heteroacene) as core, is designed and synthesized. The aromatic pyrrole ring with strong electron-donating ability in the core enhances the intramolecular charge transfer effect, finely tunes the optical bandgap and absorption profile of BDTIC, and thus results in a narrowed optical bandgap(E_g~(opt)) of 1.38 eV and a near-infrared absorption to 900 nm. When BDTIC is paired with donor polymer PBDB-T to fabricate organic solar cells, the optimized device achieves a best power conversion efficiency of 12.1% with a short-circuit current density of 20.0 mA·cm~(-2) and an open-circuit voltage of 0.88 V. The photovoltaic performance benefits from the broad absorption, weak bimolecular recombination, efficient charge separation and collection, and favorable blend morphology. This work demonstrates that thienopyrroleexpanded benzo[1,2-b:4,5-b′]dithiophene unit(heptacyclic S,N-heteroacene) is a promising building unit to construct high-performance NFAs by enhancing the intramolecular charge transfer effect, broadening absorption as well as maintaining good intermolecular stacking property.     

Development of naphtho[1,2-b:5,6-b']dithiophene based novel small molecules for efficient bulk-heterojunction organic solar cells

Two new small molecules with a rigid planar naphtho[1,2-b:5,6-b']dithiophene (NDT) unit were designed and synthesized. Solution processed bulk-hetereojunction organic solar cells based on blends of the small molecules and [6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM) exhibited promising photovoltaic device performance with a maximum power conversion efficiency up to 2.20% under the illumination of AM 1.5G, 100 mW cm(-2).     

Reactivity of the Lithium Salt of 4H-Cyclopenta[2,1-b:3,4-b']dithiophene

The regioselectivity in reactions of the lithium salt of 4H-cyclopenta[2,1-b:3,4-b']dithiophene with various electrophilic agents [SiMe₃Cl, SnMe₃Cl, D₂O, Re(CO)₅Br] is discussed in terms of the charge and orbital control concepts.     

The preparation of the benzo[4,5]cyclohepta[1,2-b]pyrazine and benzo[4,5]cyclohepta[1,2-b]quinoxaline systems

Benzo[4,5]cyclohepta[1,2-b]quinoxaIine 2 , benzo[4,5]cyclohepta[1,2-b]pyrazine 3a and benzo[4,5]cyclohepta[1,2-b]quinoxaline 4 were prepared from 4,5-benzotropolone and 1,2-phenylenediamine, ethylenediamine and 1,2-diaminocyclohexane, respectively. Compound 3a was methylated to 3b .     

Synthesis and properties of 3-hydroxypyrazolo[4,3-b]quinuclidine

The reaction of 2-ethoxycarbonyl-3-oxoquinuclidine with hydrazine hydrate and with methylhydrazine has been examined. It has been shown with the aid of the IR and NMR spectra that the products are 3-hydroxypyrazolo[4,3-b]quinuclidine and its N-methyl derivative, together with alkylation, cyanoethylation, and acylation products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 651–656, May, 1970.     

Optical properties of dibenzo[d,d']thieno[3,2-b;4,5-b']dithiophene monocrystals: the effect of intermolecular interactions

The polarized UV-visible absorption spectra of dibenzo[d,d']thieno[3,2-b;4,5-b']dithiophene single crystals are reported and interpreted to definitively attribute the observed bands and their polarizations. The results provide information on the intermolecular interactions and on the aggregation in the condensed phase, which can be of either herringbone- or H-type, depending on the electronic transition taken into considerations, with consequences on the order and polarization of the absorption bands. A relatively easy method is also discussed to obtain information on the structural/morphological properties of different types of samples, including thin films, which have been recently proposed for high-performance organic film-effect transistors for their high ionization potential and photostability.     

Synthesis, electronic properties, and X-ray structural characterization of tetrarylbenzo[1,2-b:4,5-b']difuran cation radicals

Electroactive tetraarylbenzo[1,2- b:4,5- b']difuran (BDF) and model diarylbenzofuran derivatives are synthesized and their structures are established by X-ray crystallography. Isolation and X-ray crystallographic characterization of the robust cation-radical salts of BDF derivatives confirm that a single charge in the BDFs is stabilized largely by the benzodifuran and coplanar alpha-aryl groups lying on the longitudinal axis. These findings suggest that the linear arrays of BDFs may allow the construction of molecular wires suitable for long-range electron transport.     

基于苯并二噻吩的D-A型窄带隙共轭聚合物在太阳能电池中的应用

近年来为获得有机聚合物太阳能电池更高的能量转换效率,越来越多的活性层材料被设计合成出来,尤其是给体材料。其中,基于给体单元苯并二噻吩(BDT)的D-A型窄带隙共轭聚合物更是多次刷新了有机聚合物太阳能电池效率的最高记录,目前达10.6%。本文探讨了基于苯并二噻吩的D-A型窄带隙共轭聚合物材料结构及其应用在太阳能电池中的性能参数关系,从提高开路电压、短路电流和填充因子三个方面总结出了提高基于BDT共轭聚合物太阳能电池能量转换效率的方法。