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The unconventional self-assembled nanodielectric (SAND) architecture is composed of solution-processed alternating inorganic (e.g., ZrOx and HfOx) and π-organic nanolayers (e.g., stilbazolium). As gate dielectrics, SANDs are compatible with a wide variety of organic and inorganic semiconductors and often impart superior thin-film transistor (TFT) performance in comparison to analogous inorganic-only dielectrics. The enhanced performance has been partly attributed to the interactions within the organic layers. To probe the role of the highly polarizable stilbazolium (Chr) organic layer in SAND structural organization and dielectric response, a saturated hydrocarbon chain-based self-assembling building block (Alk) was synthesized and incorporated in SAND structures. By using Chr and Alk in the different SAND organic layers, the effects of the Chr built-in dipole on bulk SAND structural and dielectric characteristics can be evaluated. The Zr-SAND structures are characterized by atomic force microscopy, X-ray reflectivity, metal-insulator-semiconductor electrical measurements, and pentacene-based organic TFTs. The layer identity and arrangement of the organic layers within the Zr-SAND structure are found to have a significant impact on the capacitor leakage current and pentacene transistor threshold voltage/turn-on voltage characteristics. Furthermore, significant cooperative interactions between adjacent Chr organic π-layers are important in enhancing these effects.

A self-assembled nanodielectric (SAND) is an ultrathin film, typically with periodic layer pairs of high-k oxide and phosphonic-acid-based π-electron (PAE) molecular layers. IPAE, having a molecular structure similar to that of PAE but with an inverted dipole direction, has recently been developed for use in thin-film transistors. Here we report that replacing PAE with IPAE in SAND-based thin-film transistors induces sizable threshold and turn-on voltage shifts, indicating the flipping of the built-in SAND polarity. The bromide counteranion (Br-) associated with the cationic stilbazolium portion of PAE or IPAE is of great importance, because its relative position strongly affects the electric dipole moment of the organic layer. Hence, a set of X-ray synchrotron measurements were designed and performed to directly measure and compare the Br- distributions within the PAE and IPAE SANDs. Two trilayer SANDs, consisting of a PAE or IPAE layer sandwiched between an HfOx and a ZrOx layer, were deposited on the SiOx surface of Si substrates or periodic Si/Mo multilayer substrates for X-ray reflectivity and X-ray standing wave measurements, respectively. Along with complementary DFT simulations, the spacings, elemental (Hf, Br, and Zr) distributions, molecular orientations, and Mulliken charge distributions of the PAE and IPAE molecules within each of the SAND trilayers were determined and correlated with the dipole inversion.

Improved understanding of fundamental structure–property relationships, particularly the effects of molecular shape and intermolecular packing on film morphology and active layer charge transport characteristics, enables more rational synthesis of new p-type small molecules. Here we investigate a series of small molecules consisting of an acene-based electron-rich core flanked by one or two electron-deficient diketopyrrolopyrrole (DPP) moieties. Through minor changes in the molecule structures, measurable variations in the crystal structure and sizable differences in macroscopic properties are achieved. The molecular symmetry as well as the conformation of the side chains affects the unit cell packing density and strength of the intermolecular electronic coupling in single crystals of all molecules in this series. The addition of a second DPP unit to the benzodithiophene (BDT) core increases molecular planarity leading to decreased reorganization energy, strong cofacial coupling, and moderate hole mobility (2.7 × 10−4 cm2 V−1 s−1). Increasing the length of the acene core from benzodithiophene to naphthodithiophene (NDT) results in a further reduction in reorganization energy and formation of smaller crystalline domains (∼11 nm) when mixed with PCBM. Decreasing the aspect ratio of the core using a “zig-zag” naphthodithiophene (zNDT) isomer results in the highest hole mobility of 1.3 × 10−3 cm2 V−1 s−1 due in part to tight lamellar (d = 13.5 A) and π–π stacking (d = 3.9 A). The hole mobility is directly correlated with the short-circuit current (11.7 mA cm−2) and solar cell efficiency (4.4%) of the highest performing zNDT:PCBM device. For each of these small molecules the calculated π-coupling constant is correlated with the hole mobility as a function of crystal structure and orientation indicating the importance of designing molecules that create extended crystalline networks with maximal π-orbital overlap.

Our objective is to demonstrate the analytical capabilities of Advanced Surface Logging or Advanced Mud Logging (AML), the results borne from an extensive use of wellsite techniques and their use in time- critical situations. The work revolves around ascertaining and characterizing from the surface the nature of fluids found downhole using a number of integrated analytical techniques on oil samples and rock cuttings. We aim to evaluate the reservoir fluid properties flowing from the fractures and fluids which are suspected to be present within the pores of the reservoir matrix via cross-referencing multiple sample mediums. The work studies data collected from a well in the Middle East; "Well-A", which was drilled as a producer from the Upper-Middle Jurassic (UMJ) Formations and an appraisal from the porous interval of the Lower Jurassic formation (LJ). The primary target of the operating company was to determine the in-situ fluid characteristics of the UMJ Formations. The communication between these two intervals as well as the contact depth is unknown and crucial at the current stage of the field development. Reservoir and hydrocarbon fluid characterization was investigated using cuttings samples taken from Well-A. All samples were analyzed in-lab, post-drilling using Advanced Mudlogging (AML) techniques such as Thermal Extraction Gas Chromatography (TEGC), Chemical Elemental Analysis and Mineralogical analysis (the latter two performed using X-Ray based techniques). Additional Mudlogging datasets gathered in real-time during drilling were integrated within the interpretation including Advanced Mud Gas (Methane to Toluene), together with the Computer Processed Image Logs and PVT test data provided by the operator. Finally, three dead oil samples from the tested intervals were analyzed in-lab with TEGC. The chromatographic analysis of the commercially produced oil from the UJ showed a bimodal distribution which was interpreted as a mix of two different maturity fluids. We were able to trace the individual levels from which these two fluids were most probable to originate, by comparing the chromatographic characteristics of these oils across the TEGC results from the cuttings analysis. Furthermore, the in-lab geochemical analysis supported the understanding of the fluid mechanism within this reservoir interval. This interpretation resulted in potentially identifying a sub interval which could yield a higher gravity oil than initially tested and potentially transform this, now unproductive interval, into a prospect. The innovative workflow, integrating all formation evaluation data collected from rock cuttings and mud gas data was applied for the first time at this level of complexity. Although prior studies investigated the potential of integrating multiple datasets to determine reservoir fluid characteristics, never before, was such an integrated approach utilized based specifically on surface logging solutions. The case study demonstrated the value of supporting interpreters to bolster their interpretations thanks to data coming from separate independent sources.

The recent emergence of a wide variety of two-dimensional (2D) materials has created new opportunities for device concepts and applications. In particular, the availability of semiconducting transition metal dichalcogenides, in addition to semi-metallic graphene and insulating boron nitride, has enabled the fabrication of all 2D van der Waals heterostructure devices. Furthermore, the concept of van der Waals heterostructures has the potential to be significantly broadened beyond layered solids. For example, molecular and polymeric organic solids, whose surface atoms possess saturated bonds, are also known to interact via van der Waals forces and thus offer an alternative for scalable integration with 2D materials. Here, we demonstrate the integration of an organic small molecule p-type semiconductor, pentacene, with a 2D n-type semiconductor, MoS2. The resulting p-n heterojunction is gate-tunable and shows asymmetric control over the anti-ambipolar transfer characteristic. In addition, the pentacene-MoS2 heterojunction exhibits a photovoltaic effect attributable to type II band alignment, which suggests that MoS2 can function as an acceptor in hybrid solar cells., Comment: 5 figures and supporting information. To appear in Nano Letters

The development of cheap and reliable time-temperature indicators (TTIs) can greatly improve customer satisfaction with respect to the correct handling and storage of perishable goods. A series of new irreversible thermochromic squaraine dyes enables the preparation of simple TTIs whose time-temperature regime can be controlled by selection of the appropriate molecule/substrate combinations.

Perylenediimides (PDIs) are among the best performing organic luminescent materials, both in terms of emission efficiency and chemical and photochemical stability because of their rigid, symmetric and planar structure; however, they exhibit very small Stokes shifts. The sizeable reabsorption of the emitted light limits the performances of perylenediimides in imaging applications and luminescent solar concentrators. Perylenemonoimides (PMIs) having an electron donating substituent in one of the free peri positions feature larger Stokes shift values while retaining high chemical stability. The selection of the most appropriate donor, both in terms of electron donating capability and steric demand, boosts emission efficiency and limits reabsorption losses. The synthesis, optical spectroscopy, molecular orbital computations, UPS, electrochemical, spectroelectrochemical, and multinuclear NMR investigation of a series of PMI derivatives functionalized with donors having different electronic characteristics and steric demands are discussed. Results are relevant for the fabrication of single layer plastic luminescent solar concentrators (LSC).

We compare and contrast the properties of hybrid organic-inorganic self-assembled nanodielectrics (SANDs) based on alternating layers of solution-processed ZrOxand either of two phosphonic acid-functionalized azastilbazolium Ï -units having opposite dipolar orientations. Conventional Zr-SAND and new inverted IZr-SAND are characterized by Kevin probe, optical spectroscopy, capacitance-voltage measurements, AFM, X-ray reflectivity, and electronic structure computation. The molecular dipolar orientation affects thin-film transistor (TFT) threshold and turn-on voltages for devices based on either p-channel pentacene or n-channel copper perfluorophthalocyanine. Specifically, Zr-SAND shifts the threshold and turn-on voltages to more positive values, whereas IZr-SAND shifts them in the opposite direction. Capping these SANDs with -SiMe3groups enhances the effect, affording a 1.3 V difference in turn-on voltage for IZr-SAND vs Zr-SAND-gated organic TFTs. Such tunability should facilitate the engineering of more complex circuits

Soluble molecular semiconductors are a promising alternative to semiconducting polymers in the field of organic photovoltaics. Here, three custom-made symmetric 1,3-bis(N,N-alkylated-2,6-dihydroxy-anilino)squaraines containing systematic variations in their molecular structures are compared regarding their applicability as donor materials in bulk-heterojunction solar cells. The terminal substitution pattern of the squaraines is varied from cyclic over linear to branched including a stereogenic center. Single crystal structures are determined, and, in the case of chiral squaraine, unusual formation of stereoisomer co-crystals is revealed. The thin film absorbance spectra show characteristic signatures of H- and J-bands or hint at the formation of tautomers. The general feasibility of these model compounds for photovoltaic applications is studied by light-induced electron spin resonance spectroscopy. The impact of the different molecular substitution patterns on aggregation behavior and, consequently, their optoelectronic solid state properties including charge carrier mobility and finally the solar cell performance are investigated.

The design, synthesis and characterization of five diphenylhydrazone end capped molecules as donors for Bulk Heterojunction (BHJ) solar cells are described. The use of the hydrazone donor instead of the more common amine one is advantageous in terms of synthetic access and overall stability. We show that the variation of both the nature and the substitution pattern of the electron deficient conjugated bridge enables the tuning of the optical energy gap as well as of the HOMO and LUMO. In particular, our data show that the low energy shift of the HOMO level along the series of hydrazone compounds, one of the critical parameters affecting the performance of BHJ cells, is as high as 0.42 eV. We tested all derivatives as donors in a BHJ configuration, using the fullerene derivative [6,6]-phenyl-C-71-butyric acid methyl ester (PC71BM) as the acceptor. We found that the trend we observed in the progressive stabilization of the chromophore HOMO level upon increasing the electron accepting capabilities of the conjugated bridge is reflected in the progressive increase of the cell open circuit voltage (V-oc). Our preliminary results show that it is possible to obtain a V-oc as high as 0.74 V, along with a power conversion efficiency of 1.2%.

The influence of solubilizing substituents on the photovoltaic performance and thin-film blend morphology of new benzo[1,2-b:6,5-b']dithiophene (bBDT) based small molecule donor semiconductors is investigated. Solar cells based on bBDT(TDPP)2-PC71BM with two different types of side chains exhibit high power conversion efficiencies, up to 5.53%.

Highly efficient plastic based single layer Luminescent Solar Concentrators (LSCs) require the design of luminophores having complete spectral separation between absorption and emission spectra (large Stokes shift). We describe the design, synthesis and characterization of a new perylene dye possessing Stokes shift as high as 300 meV, fluorescent quantum yield in the LSC slab of 70% and high chemical and photochemical stability. © 2013 The Royal Society of Chemistry.