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Nano-porous Ta2O5 thin film electrodes are prepared by magnetron sputtering at low pressure in the presence of an oxygen atmosphere with an inert gas. The sputtered Ta2O5 thin film is subsequently annealed at 350∘C for 2 h in high pure N2 (Ta2O5-350) to introduce oxygen deficiency. The Ta2O5-350 electrode possesses highly reversible lithium ion storage and good rate capability, which has high specific capacities of about 480 mAh g − 1 at a rate of 0.1 C. Furthermore, after 2000 cycles at a rate of 5 C the Ta2O5-350 electrode shows no obvious capacity decay and retains specific capacity of about 160 mAh g − 1 . The excellent lithium storage properties of Ta2O5-350 electrode can be correlated to the nano-porous electrode architecture and oxygen deficiency. Nano-porous Ta2O5 thin film electrodes as anode of lithium ion battery have been successfully prepared via a convenient magnetron sputtering and subsequently low temperature annealing method. The Ta2O5-350 electrode possesses highly reversible lithium ion storage and good rate capability due to the nano-porous structure and oxygen defects. [ABSTRACT FROM AUTHOR]

In this paper, a new cruciform donor-acceptor molecule 2,2'-((5,5'-(3,7-dicyano-2,6-bis(dihexylamino)benzo[1,2-b:4,5-b']difuran-4,8-diyl)bis(thiophene-5,2-diyl))bis (methanylylidene))dimalononitrile ( BDFTM) is reported. The compound exhibits both remarkable solid-state red emission and p-type semiconducting behavior. The dual functions of BDFTM are ascribed to its unique crystal structure, in which there are no intermolecular face-to-face π-π interactions, but the molecules are associated by intermolecular CN...π and H-bonding interactions. Firstly, BDFTM exhibits aggregation-induced emission; that is, in solution, it is almost non-emissive but becomes significantly fluorescent after aggregation. The emission quantum yield and average lifetime are measured to be 0.16 and 2.02 ns, respectively. Crystalline microrods and microplates of BDFTM show typical optical waveguiding behaviors with a rather low optical loss coefficient. Moreover, microplates of BDFTM can function as planar optical microcavities which can confine the emitted photons by the reflection at the crystal edges. Thin films show an air-stable p-type semiconducting property with a hole mobility up to 0.0015 cm2V−1s−1. Notably, an OFET with a thin film of BDFTM is successfully utilized for highly sensitive and selective detection of H2S gas (down to ppb levels). [ABSTRACT FROM AUTHOR]

Two conjugated molecules, TADPP3 and TADPP2-TT, are reported, in which three and two dithienyldiketopyrrolopyrrole (DPP) moieties, respectively, are substituted at the meta positions of benzene. Based on cyclic voltammetry and absorption data, TADPP3 and TADPP2-TT possess similar HOMO and LUMO energies of about −5.2 and −3.4 eV, respectively. Thin films of TADPP3 and TADPP2-TT exhibit p-type semiconducting behavior with hole mobilities of 2.36×10−3 and 3.76×10−4 cm2 V−1 s−1 after thermal annealing. Molecules TADPP3 and TADPP2-TT were utilized as p-type photovoltaic materials to fabricate organic solar cells after blending with phenyl C71 butyric acid methyl ester ( PC71BM) and phenyl C61 butyric acid methyl ester ( PC61BM). The relatively low JSC and fill factor values can be attributed to poor film morphologies based on AFM and XRD studies. A solar cell with a thin film of TADPP3 with PC71BM in a weight ratio of 1:2 exhibits a high open-circuit voltage ( VOC) of 0.99 V and a power conversion efficiency (PCE) of 2.47 %. Interestingly, TADPP3 can also be employed as an n-type photovoltaic material. The blended thin film of TADPP3 with P3HT in a weight ratio of 1:2 gave a high VOC of 1.11 V and a PCE of 1.08 % after thermal annealing. [ABSTRACT FROM AUTHOR]

Inthis paper, we report the design, synthesis and semiconductingbehavior of two conjugated D–A polymers P-BPDTTand P-BPDBTwhich entail BPD, a Pechmanndye framework, as electron accepting moieties, and thieno[3,2-b]thiophene and 2,2′-bithiophene as electron donatingmoieties. Their HOMO/LUMO energies and bandgaps were estimated basedon the respective cyclic voltammgrams and absorption spectra of thinfilms. P-BPDTTpossesses lower LUMO level and narrowerbandgap than P-BPDBT. On the basis of the characterizationof the field-effect transistors, a thin film of P-BPDTTexhibits ambipolar semiconducting properties with hole and electronmobilities reaching 1.24 cm2V–1s–1and 0.82 cm2V–1s–1, respectively, after thermal annealing. In comparison,thin film of P-BPDBTonly shows p-typesemiconducting behavior with hole mobility up to 1.37 cm2V–1s–1. AFM and XRD studieswere presented to understand the interchain arrangements on the substratesand the variation of carrier mobilities. [ABSTRACT FROM AUTHOR]

Two diketopyrrolopyrrole (DPP)-based donor-acceptor (D-A) conjugated molecules, DPP-F and DPP-2F, which contain E-(1,2-difluorovinyl) moieties, are reported. The LUMO energies of DPP-F and DPP-2F were estimated to be −3.49 and −3.70 eV, respectively, based on their redox potentials and absorption spectral data; these values were clearly lowered because of the incorporation of electron-withdrawing E-(1,2-difluorovinyl) moieties. Organic field-effect transistors (OFETs) with thin films of DPP-F and DPP-2F were successfully fabricated with conventional techniques. Based on the respective transfer and output characteristics measured in an inert atmosphere, thin films of DPP-2F display ambipolar semiconducting behavior with hole and electron mobilities reaching 0.42 and 0.80 cm2 V−1 s−1, respectively. The as-prepared OFET of DPP-2F already shows high hole and electron mobilities that are not influenced remarkably by thermal annealing. For thin films of DPP-F, only p-type semiconducting behavior was observed in both an inert atmosphere and air, and the hole mobility increased to 0.1 cm2 V−1 s−1 after thermal annealing. XRD and AFM studies were performed with thin films of DPP-F and DPP-2F after annealing at different temperatures. [ABSTRACT FROM AUTHOR]

Ambipolar organic semiconductors that can conduct both hole and electron carriers have received increasing attention in recent years. In their Full Paper on page   1068   ff., Deqing Zhang and co ‐ workers report two conjugated molecules containing E ‐ (1,2 ‐ difluorovinyl) and diketopyrrolopyrrole (DPP) moieties. One of them, DPP ‐ 2F, displays an ambipolar semiconducting behavior with hole and electron mobilities reaching 0.42 and 0.80   cm2   V−1   s−1, respectively. The present study clearly demonstrates that (E) ‐ 2 ‐ (1,2 ‐ difluorovinyl) is a useful electron ‐ withdrawing block to tune frontier orbital energies and extend conjugation. [ABSTRACT FROM AUTHOR]

Z. T. Liu, G. X. Zhang, S.‐X. Liu, D. Q. Zhang, and co‐workers report a new cruciform donor–acceptor molecule, BDFTM, exhibiting both remarkable solid‐state red emission and p‐type semiconducting behavior. On page 4250, crystalline microrods and microplates of BDFTM show typical optical waveguiding behaviors with a rather low optical loss co‐efficient. Notably, an organic field‐effect transistor with a thin film of BDFTM is successfully utilized for the highly sensitive and selective detection of H2S gas, down to ppb levels. [ABSTRACT FROM AUTHOR]

Three diketopyrrolopyrrole (DPP)-quaterthiophene conjugated polymers, pDPP4T-1, pDPP4T-2, and pDPP4T-3, in which the molar ratios of the urea-containing alkyl chains vs branching alkyl chains are 1:30, 1:20, and 1:10, respectively, were prepared and investigated. In comparison with pDPP4T without urea groups in the alkyl side chains and pDPP4T-A, pDPP4T-B, and pDPP4T-C containing both linear and branched alkyl chains, thin films of pDPP4T-1, pDPP4T-2, and pDPP4T-3 exhibit higher hole mobilities; thin-film mobility increases in the order pDPP4T-1 < pDPP4T-2 < pDPP4T-3, and hole mobility of a thin film of pDPP4T-3 can reach 13.1 cm(2) V(-1) s(-1) after thermal annealing at just 100 °C. The incorporation of urea groups in the alkyl side chains also has an interesting effect on the photovoltaic performances of DPP-quaterthiophene conjugated polymers after blending with PC71BM. Blended thin films of pDPP4T-1:PC71BM, pDPP4T-2:PC71BM, and pDPP4T-3:PC71BM exhibit higher power conversion efficiencies (PCEs) than pDPP4T:PC71BM, pDPP4T-A:PC71BM, pDPP4T-B:PC71BM, and pDPP4T-C:PC71BM. The PCE of pDPP4T-1:PC71BM reaches 6.8%. Thin films of pDPP4T-1, pDPP4T-2, and pDPP4T-3 and corresponding thin films with PC71BM were characterized with AFM, GIXRD, and STEM. The results reveal that the lamellar packing order of the alkyl chains is obviously enhanced for thin films of pDPP4T-1, pDPP4T-2, and pDPP4T-3; after thermal annealing, slight inter-chain π-π stacking emerges for pDPP4T-2 and pDPP4T-3. Blends of pDPP4T-1, pDPP4T-2, and pDPP4T-3 with PC71BM show a more pronounced micro-phase separation. These observations suggest that the presence of urea groups may further facilitate the assemblies of these conjugated polymers into nanofibers and ordered aggregation of PC71BM.

Two conjugated molecules, TADPP3 and TADPP2-TT, are reported, in which three and two dithienyldiketopyrrolopyrrole (DPP) moieties, respectively, are substituted at the meta positions of benzene. Based on cyclic voltammetry and absorption data, TADPP3 and TADPP2-TT possess similar HOMO and LUMO energies of about -5.2 and -3.4 eV, respectively. Thin films of TADPP3 and TADPP2-TT exhibit p-type semiconducting behavior with hole mobilities of 2.36×10(-3) and 3.76×10(-4)  cm(2)  V(-1)  s(-1) after thermal annealing. Molecules TADPP3 and TADPP2-TT were utilized as p-type photovoltaic materials to fabricate organic solar cells after blending with phenyl C71 butyric acid methyl ester (PC71BM) and phenyl C61 butyric acid methyl ester (PC61BM). The relatively low JSC and fill factor values can be attributed to poor film morphologies based on AFM and XRD studies. A solar cell with a thin film of TADPP3 with PC71BM in a weight ratio of 1:2 exhibits a high open-circuit voltage (VOC) of 0.99 V and a power conversion efficiency (PCE) of 2.47 %. Interestingly, TADPP3 can also be employed as an n-type photovoltaic material. The blended thin film of TADPP3 with P3HT in a weight ratio of 1:2 gave a high VOC of 1.11 V and a PCE of 1.08 % after thermal annealing., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The simple one-pot syntheses of sulfur-rich thiepin-fused heteroacences with an alkylidene-fluorene framework, THA1 and THA6 (thiepin-fused heteroacene 1 or 6, in which the thiepin is conjugated at both ortho positions with SCH3 or SC6 H13 , respectively), is reported. Based on electrochemical studies and theoretical calculations, their LUMO energies are relatively low (-3.26 eV), and their HOMO and HOMO-1 orbitals are nearly degenerate. The thiepin ring contributes mainly to HOMO-1 and LUMO orbitals, however, HOMO orbitals dominantly reside on thienoacence rings. Within the crystal of THA1, the molecules adopt a herringbone arrangement and multiple intermolecular interactions lead to the formation of a 2D network. Interestingly, THA6 shows totally different intermolecular arrangements. Organic field-effect transistor (OFET) devices show both compounds exhibiting p-type semiconducting behavior. Thin films or microcrystals of THA1 possess relatively high hole mobility. Moreover, the mobilities of the microcrystal of THA1 along three directions are in the same order, thus the hole-carrier transporting within the hexagonal-plane of microcrystal of THA1 exhibits less anisotropic behavior. In comparison, both thin films and microrods of THA6 show low hole mobilities. This agrees well with the intermolecular arrangements and interactions within crystal of THA6. Further theoretical calculations reveal that significant intermolecular electronic coupling among HOMO-1 orbitals and sulfur atoms play an important role in intermolecular electronic coupling for THA1., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)