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Herein we study isothermal spherulitic crystallization in multicomponent thin films under solvent-vapor annealing. Spherulitic crystallization is taken as a coherent phase transition between an amorphous phase and a crystalline phase. Both of the two phases of the film are modeled as (possibly prestressed) elastic solids, and no a priori assumption is made on the stresses in the two phases. The interface between the two bulk phases is treated as an evolving one-dimensional open thermodynamic system defined by various thermodynamic variables. In particular, each chemical component of the interface is generally endowed with a mass density and a chemical potential. The interface, as a continuum system, is composed of particles. We assign each particle of an evolving interface a well-defined interface velocity so that a moving interface with mass density carries linear momentum and kinetic energy. By appealing to free energy imbalance for isothermal processes and balance of mass and momentum, we derive dissipation inequalities for the bulk phases and for the interface, with which we obtain constitutive restrictions through the Coleman–Noll procedure. The driving force behind spherulitic crystallization is identified as the quantity conjugate to the normal velocity in the interfacial dissipation inequality. Finally we investigate the effect of prestress on the directional dependence of spherulitic growth. [ABSTRACT FROM AUTHOR]

Abstract: While prior efforts have demonstrated that the morphologies of block copolymer (BC) bulk films can be controlled through judicious chemical design and thermal annealing, recent interest has focused on regulating the orientation of BC nanostructures and minimizing defects. Thermal processes developed to achieve this purpose for nonpolar BCs are not, however, suitable for orienting microphase‐ordered BCs composed of at least one block with charged moieties that can form thermally stable ionic clusters. To overcome this challenge, we have previously applied solvent‐vapor (SV) annealing to block ionomer (BI) bulk films composed of midblock‐sulfonated pentablock copolymers and established that this approach yields highly ordered morphologies that display evidence of improved in‐plane orientation. Here, we employ small‐angle X‐ray scattering to compare the effectiveness of three solvent‐related processes–SV annealing, SV permeation, and SV sorption–on BI ordering and grain growth, and offer explanations for observed differences on the basis of thermodynamic‐ and transport‐related considerations. Differences in the experimental design of these solvent‐related processes are found to affect nanostructural development, as evidenced by the extent of in‐plane grain growth. [ABSTRACT FROM AUTHOR]

Bottom-gate top-contact organic field-effect transistors (OFETs) based on 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and poly(methyl methacrylate) (PMMA) blends were fabricated using electrostatic spray deposition (ESD). Solvent-vapor annealing (SVA) was conducted as a post-deposition treatment to induce vertical phase separation of the blend films. The phase-separated morphology was investigated by selective etching of TIPS pentacene with cyclohexane. A relatively rough surface with some pinholes was observed in the etched film without SVA, suggesting that vertical phase separation was not sufficient during the ESD process. The phase-separated morphology was modified remarkably by SVA, and a SVA-treated blend device with a well-defined phase-separated structure exhibited enhanced performance and operational stability compared to a device based on the as-deposited blend. [ABSTRACT FROM AUTHOR]

A novel homoleptic sandwich-type tris[2,3,9,10,16,17,23,24-octa(naphthoxy)phthalocyaninato] europium triple-decker complex Eu 2 [Pc(ONh) 8 ] 3 ( 1 ), having a low-lying LUMO energy level of – 4.0 eV and relatively narrow HOMO–LUMO separation of 1.13 eV, was designed and successfully synthesized. The OFET devices fabricated from this compound using a solution-based quasi-Langmuir-Shäfer (QLS) method display air-stable ambipolar performance with the carrier mobilities of (2.5 ± 0.5) × 10 − 6 cm 2 V − 1 s − 1 for holes and (2.3 ± 0.3) × 10 − 6 cm 2 V −1 s −1 for electrons, indicating its ambipolar semiconducting nature. Upon the o -dichlorobenzene (DCB) solvent vapor annealing at the temperature of 60, 80, 100, and 120 °C, a fine combination of the “oriented attachment” with Ostwald ripening process under controlled SVA environments leads to the growth of the first two-dimensional (2D) micro-sheet microstructures with tunable morphology including the fragment-like irregular polygons, quasi-four-corner sheets, squares, and clovers, respectively, from the nanoparticles of the pristine QLS film. This in turn results in the tunable OFET device performance with the carrier mobilities changing as a result of the morphologies and crystallinities. The best result was achieved for the most crystalline 2D squares-based devices with the carrier mobilities of 0.11 ± 0.03 cm 2 V − 1 s − 1 for holes and 0.06 ± 0.02 cm 2 V − 1 s − 1 for electrons. [ABSTRACT FROM AUTHOR]

We studied the effects of solvent-vapor annealing (SVA) on the device performance of bulk-heterojunction organic photovoltaic solar cells. Electrostatic spray deposition (ESD) was used to prepare photoactive layers composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) blend. While the surface of the photoactive layer could be flattened by SVA, excessive treatment resulted in a decrease in open-circuit voltage. We attribute this to too large vertical phase separation within the P3HT:PCBM blend and accumulation of P3HT on the surface of the photoactive layer, which can induce recombination of photogenerated charges at the cathode/photoactive layer interface. A decrease in the open-circuit voltage could be prevented to some extent by depositing the photoactive layers using smaller droplets produced in the ESD process; this was probably due to the slower progress of vertical phase separation. Furthermore, introducing LiF as a hole-blocking layer between the cathode and the photoactive layer significantly reduced recombination-related leakage current, thereby preventing a decrease in open-circuit voltage. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solvent–vapor annealing is employed to reconstruct the morphology of PCDTBT:PC71BM thin films. [•] We demonstrate evidence for a nanoscale optimization tool for dispersing the PC71BM aggregates. [•] The impact of optimized morphology on photovoltaic performance is examined. [•] The improved PV performance is attributed to well-dispersed fullerene phase. [ABSTRACT FROM AUTHOR]

Abstract: A systematical investigation on solvent-vapor annealing in polymer thin film transistors is performed using a thiazolothiazole-bithiazole conjugated polymer as the active layer. Film morphology, packing order and device performance are closely related to polarity and solubility parameter of the annealing solvent and annealing time. The formation of highly ordered and closely connected fibrillar domains is realized by using a solvent with similar solubility parameter and polarity to the conjugated polymer. Field-effect transistors based on pristine polymer films exhibit a highest charge carrier mobility of 0.0067cm2 V−1 s−1. After solvent vapor annealing with THF for 48h, the mobility boosts up to 0.075cm2 V−1 s−1. This correlation between solvent polarity, solubility parameter and film morphology, packing order and mobility provides a useful guideline towards high performance polymer thin film transistors with solvent-vapor annealing method. [Copyright &y& Elsevier]

A method for patterning organic single-crystal transistor arrays via surface selective deposition is presented. Solvent-vapor annealing is applied for the formation of organic crystals under ambient conditions. The devices are fabricated with a dual-gate structure, which allows the investigation of device performances of bottom-gate/top-contact (BG/TC) and top-gate/top-contact (TG/TC) structures based on the same crystals. The resulting BG/TC devices exhibit the field-effect mobility (μFET) up to 3.5 cm2/Vs. And μ FET is influenced by the contact resistance, resulting in large variation in device performance. On the other hand, TG/TC structure exhibits better performance with smaller variation. The highest μ FET is 7.4 cm2/Vs. [ABSTRACT FROM PUBLISHER]

Abstract: Solvent–vapor annealing was used to increase the field-effect mobility of soluble triethylsilylethynyl anthradithiophene spin-coated on organosilane-terminated silicon dioxide, yielding a high value of 1.2cm2 V−1 s−1. The cause of improvement was investigated by atomic force microscopy, X-ray diffraction, and near-edge X-ray absorption fine structure spectroscopy. Vapor annealing exerts little effect on the molecular tilt and the crystallinity normal to the surface, but improves the film morphology significantly, yielding larger grains with perhaps better in-plane crystallinity. [ABSTRACT FROM AUTHOR]

Abstract: The challenge of generating crystals of organic materials has been pursued by many research groups who aim to develop materials sets for active electronic and optoelectronic devices, including field-effect transistors [C.D. Dimitrakopoulos, P.R.L. Malenfant, Adv. Mater. 14 (2002) 99; H.E. Katz, Z. Bao, J. Phys. Chem. B 104 (2000) 671; Y.Y. Lin, D.J. Gundlach, S.F. Nelson, T.N. Jackson, IEEE Trans. Electron Dev. 44 (1997) 1325], photodetectors [P. Peumans, V. Bulović, S.R. Forrest, Appl. Phys. Lett. 76 (2000) 2650] and optical modulators [S.R. Marder, J.W. Perry, C.P. Yakymyshyn, Chem. Mater. 6 (1994) 1137]. Here we describe a method for in-plane growth of millimeter-scale crystalline organic needles from initially amorphous thin films of the molecular organic semiconductor tris(8-hydroxyquinoline)aluminum (Alq3). The needles form when the vacuum-deposited amorphous films are exposed to chloroform vapor at room temperature and pressure, and can be as large as several microns thick, several microns wide, and one centimeter long (limited in length by the substrate dimensions). As such, the Alq3 needles are more than 1000 times longer than any previously reported organic crystals formed via a similar solvent-vapor annealing process [F. Iwatsu, T. Kobayashi, N. Uyeda, J. Phys. Chem. 84 (1980) 3223; F. Iwatsu, J. Cryst. Growth 71 (1985) 629; A.M. Hor, R.O. Loutfy, Thin Solid Films 106 (1983) 291; B.A. Gregg, J. Phys. Chem. 100 (1996) 852; J.C. Conboy, E.J.C. Olson, D.M. Adams, J. Kerimo, A. Zaban, B.A. Gregg, P.F. Barbara, J. Phys. Chem. B 102 (1998) 4516; M. Brinkmann, J.C. Wittmann, C. Chaumont, J.J. Andre, Thin Solid Films 292 (1997) 192; F. Toffolo, M. Brinkmann, O. Greco, F. Biscarini, C. Taliani, H.L. Gomes, I. Aiello, M. Ghedini, Synth. Met. 101 (1999) 140]. Moreover, the Alq3 needles are spatially separated from one another and oriented with their long axes parallel to lithographically pre-defined periodic submicron grooves in the substrate surface. [Copyright &y& Elsevier]

Accessing vertical orientation of two-dimensional (2D) perovskite films is key to achieving high-performance solar cells with these materials. Herein, we report on solvent-vapor annealing (SVA) as a general postdeposition strategy to induce strong vertical orientation across broad classes of 2D perovskite films. We do not observe any local compositional drifts that would result in impure phases during SVA. Instead, our experiments point to solvent vapor plasticizing 2D perovskite films and facilitating their surface-induced reorientation and concomitant grain growth, which enhance out-of-plane charge transport. Solar cells with SVA 2D perovskites exhibit superior efficiency and stability compared to their untreated analogs. With a certified efficiency of (18.00 ± 0.30) %, our SVA (BDA)(Cs 0.1 FA 0.9 ) 4 Pb 5 I 16 solar cell boasts the highest efficiency among all solar cells with 2D perovskites ( n ≤ 5) reported so far.

It is discovered that the molecular packing and the orientation of crystallite arrangement in the film state are critical to the performance of the typical sandwich organic‐based memory devices (OMDs). Here, a solvent‐vapor annealing (SVA) strategy is firstly developed for amphipathic molecules to regulate the film morphology and intermolecular stacking, so as to obtain the satisfied performance. Through the screening of SVA solvents, an evidently upgraded nonvolatile memory behavior based on MeOH‐annealed film with superior reproducibility, a low switching voltage of −2.3 V and high ON/OFF ratio of 104 are observed. This work not only gives a fresh application of the amphipathic materials to OMDs, but really provides a general guiding significance for SVA solvent selection to achieve controllable crystallite orientation and effective OMDs performance. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) nanowires have attracted great interest, while air-stable n-type 1D nanowires still remain scarce. Herein, we present solvent-vapor annealing (SVA) made nanowires based on perylene tetracarboxylic diimide (PDI) derivative. It was found that the spin-coated thin films reorganized into nanowires distributed all over the substrate, as a result of the following solvent-vapor annealing effect. Cooperating with the atomic force microscopy and fluorescence microscopy characterization, the PDI8-CN2 molecules were supposed to conduct a long-range and entire transport to form the 1D nanowires through the SVA process, which may guarantee its potential morphology tailoring ability. In addition, the nanowire-based transistors displayed air stable electron mobility reaching to 0.15 cm2 V−1 s−1, attributing to effective in situ reassembly. Owing to the broader application of organic small-molecule nanowires, this work opens up an attractive approach for exploring new high-performance micro- and nanoelectronics. [ABSTRACT FROM AUTHOR]

We demonstrate the generation of block copolymer (BCP) line patterns oriented orthogonal to a very small (minimal) topographic trench pattern over arbitrarily large areas using solvent-vapor annealing. Increasing the thickness of BCP films induced an orthogonal alignment of the BCP cylindrical microdomains, where full orthogonal alignment of the cylindrical microdomains with respect to the trench direction was obtained at a film thickness corresponding to 1.70 L 0 . A capillary flow of the solvent across the trenches was a critical factor in the alignment of the cylindrical microdomains. Grazing incidence small-angle X-ray scattering was used to determine the orientation function of the microdomains, with a value of 0.997 being found reflecting a nearly perfect orientation. This approach to produce orthogonally aligned BCP line patterns could be extended to the nanomanufacturing and fabrication of hierarchical nanostructures.

The directed self-assembly of diblock copolymer chains (poly(1,1-dimethyl silacyclobutane)-block-polystyrene, PDMSB-b-PS) into a thin film double gyroid structure is described. A decrease of the kinetics of a typical double-wave pattern formation is reported within the 3D-nanostructure when the film thickness on mesas is lower than the gyroid unit cell. However, optimization of the solvent-vapor annealing process results in very large grains (over 10 µm²) with specific orientation (i.e., parallel to the air substrate) and direction (i.e., along the groove direction) of the characteristic (211) plane, demonstrated by templating sub-100-nm-thick PDMSB-b-PS films., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two twisted singly linked perylene bisimide (PBI) dimers with chalcogen bridges in the PBI cores, named C4,4-SdiPBI-S and C4,4-SdiPBI-Se, were synthesized as acceptors for nonfullerene all-small-molecule organic solar cells (NF all-SMSCs). A moderate-band-gap small-molecule DR3TBDTT used as the electron donor displayed complementary absorption with C4,4-SdiPBI-S and C4,4-SdiPBI-Se. It was found that solvent-vapor annealing (SVA) played a critical role in the photovoltaic performance in NF all-SMSCs, which improves the crystallinity of the donor and acceptors, promotes the proper phase segregation domain size, and therefore enhances charge transport. The power conversion efficiencies (PCEs) of NF all-SMSC devices based on DR3TBDTT/C4,4-SdiPBI-S and DR3TBDTT/C4,4-SdiPBI-Se increased from 2.52% to 5.81% (J SC = 11.12 mA cm -2 , V OC = 0.91 V, and FF = 57.32%) and from 2.65% to 6.22% (J SC = 11.55 mA cm -2 , V OC = 0.92 V, and FF = 58.72%), respectively, after exposure to chloroform vapor. The best efficiency of 6.22% is one of the highest PCEs for NF all-SMSC-based PBI acceptors so far. The studies illustrate that highly efficient NF all-SMSCs can be achieved by using a PBI acceptor with a suitable SVA process.