High-resolution scanning tunneling microscopy (STM) is a promising method for characterizing organic semiconductors to obtain a deep understanding of organic semiconductor physics. However, organic films on conductive single-crystal substrates, which are required for STM, usually present different growth behaviors than the films on inert substrates such as SiO2. Here, we reported a simple modification method for modulating the organic semiconductor film growth on the highly oriented pyrolytic graphite (HOPG) and Au(111) substrates and investigated the detailed morphology evolution. Self-assembled monolayers (SAMs) fabricated from vacuum deposition and solution processing were introduced on these conductive substrates. Pentacene, a prototypical organic semiconductor, presented quasi-layer-by-layer growth on HOPG or Au(111) sufaces modified with solution-processed alkane monolayer. The pentacene film resembled the upright packing and terraced morphology but with larger grain size than that of thin-film phase on SiO2. The introduced n-dotriacontane layer decreased the interaction between pentacene adsorbates and the active substrate and provided a lower surface energy which supported the upright orientation of pentacene. Modification of the substrates with alkanes provides a feasible approach to grow high-quality organic thin films that are suitable for characterization down to the molecular level. Additionally, this approach is effective for two-dimensional substrate materials such as graphene and is not limited to single-crystal substrates.

Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

Integrating covalent organic frameworks (COFs) with other functional materials is a useful route to enhancing their performances and extending their applications. We report herein a simple encapsulation method for incorporating catalytically active Au nanoparticles with different sizes, shapes, and contents in a two-dimensional (2D) COF material constructed by condensing 1,3,5-tris(4-aminophenyl)benzene (TAPB) with 2,5-dimethoxyterephthaldehyde (DMTP). The encapsulation is assisted by the surface functionalization of Au nanoparticles with polyvinylpyrrolidone (PVP) and follows a mechanism based on the adsorption of nanoparticles onto surfaces of the initially formed polymeric precursor of COF. The incorporation of nanoparticles does not alter obviously the crystallinity, thermal stability, and pore structures of the framework matrices. The obtained COF composites with embedded but accessible Au nanoparticles possess large surface areas and highly open mesopores and display recyclable catalytic performance for reduction of 4-nitrophenol, which cannot be catalyzed by the pure COF material, with activities relevant to contents and geometric structures of the incorporated nanoparticles.Keywords: catalysis; composites; covalent organic framework; nanoparticles; porous materials;

Random lasers have been extensively and intensively investigated due to their fundamental importance and promising applications. Here, we explored the lasing behavior of carbon quantum dot (CQD)/Rhodamine B (RhB) composites. CQDs exhibited a broad emission spectrum which overlapped with the absorption spectrum of the RhB dye. We investigated an approach wherein the –OH, –NH2 and –PO4 group functionalized CQD/RhB composites showed lasing behavior. The optical pumping of functionalized CQD/RhB composites exhibited lasing emission which is dynamically tunable as a function of the surface properties of CQDs at the laser wavelength of 532 nm by varying the pump energy. The PO4-CQD/RhB composites showed a typical lasing emission with a linewidth of 3.2 nm at 587 nm at 1.86 mJ pump energy. We also demonstrated that the pH value of CQD solution played a key role on the lasing behavior of CQD/composites.

Post-annealing was conducted to investigate the control efficiency of template-directed growth of organic molecules. Disordered organic patterns can be converted to ordered ones via elimination of randomly distributed molecular islands by annealing, resulting in full control of organic molecules on templates with tunable spacing. Molecular dynamics (MD) simulations revealed that the strong interaction between the molecule and the template plays a key role in tuning the control efficiency. With this method, direct growth of multicolor patterns is demonstrated.

Developments in micro-displays have led to great interest in patterning OLEDs on the microscale. However, because organic molecules are fragile in adverse environments, patterning OLEDs on the microscale remains underdeveloped. In this work, the fabrication of Micro-OLEDs via the area-selective growth of hole-transporting material is reported. The active material is selectively deposited on pre-determined areas, and this technique is compatible with photolithography. High-resolution OLEDs with feature sizes as low as sub-micrometer and green-, orange-red- and deep-blue-emitting devices are demonstrated. This technique provides a promising method for the fabrication of high-resolution OLED devices over large areas.

A direct printing of liquid droplet matrix on various surfaces is demonstrated using a stamp that can be recycled for over 100 times. The technique can be applied to pattern functional organic materials and nanoparticles and fabricate microlens arrays in one step. By controlling the printing pressure and the surface wettability, a feature size that is smaller than that of the stamp was achieved in a tunable manner.

Random lasing is desired in plasmonics nanostructures through surface plasmon amplification. In this study, tunable random lasing behavior was observed in dye molecules attached with Au nanorods (NRs), Au nanoparticles (NPs) and Au@Ag nanorods (NRs) respectively. Our experimental investigations showed that all nanostructures i.e., Au@AgNRs, AuNRs & AuNPs have intensive tunable spectral effects. The random lasing has been observed at excitation wavelength 532 nm and varying pump powers. The best random lasing properties were noticed in Au@AgNRs structure, which exhibits broad absorption spectrum, sufficiently overlapping with that of dye Rhodamine B (RhB). Au@AgNRs significantly enhance the tunable spectral behavior through localized electromagnetic field and scattering. The random lasing in Au@AgNRs provides an efficient coherent feedback for random lasers.

We report a new pathway to fabricate armchair graphene nanoribbons with five carbon atoms in the cross section (5-AGNRs) on Cu(111) surfaces. Instead of using haloaromatics as precursors, the 5-AGNRs are synthesized via a surface assisted decarboxylation reaction of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). The on-surface decarboxylation of PTCDA can produce extended copper–perylene chains on Cu(111) that are able to transform into graphene nanoribbons after annealing at higher temperatures (ca. 630 K). Due to the low yield (ca. 20%) of GNRs upon copper extrusion, various gases are introduced to assist the transformation of the copper–perylene chains into the GNRs. Typical reducing gases (H2 and CO) and oxidizing gas (O2) are evaluated for their performance in breaking aryl–Cu bonds. This method enriches on-surface protocols for the synthesis of AGNRs using non-halogen containing precursors.

Abstract1D nanoparticle arrangements have gained widespread attention because of their unique collective physical properties and potential applications in functional devices. To push the device integration toward its intrinsic limits, the precise positioning of colloidal nanoparticles into 1D layout is still a challenging task, especially for nanoparticles in the sub-20 nm range. In this work, a novel strategy based on the synergistic modulation of lateral and bottom electrostatic potential of grooves is applied, thus demonstrating a high-resolution confinement of 1D colloidal nanoparticle arrays. The mechanism of spatial potential modulation is elucidated in details, through the combination of quantitative theoretical modeling and consistent experimental results. A crystal-clear guide for the development of novel applications with both fundamental and technological perspectives is therefore provided.

AbstractOne of the main challenges to achieve high-performance bottom-contact transistors involves the organic/electrodes contacts. This study provides a simple approach to address the contact issue by incorporating an inducing layer prior to the organic semiconductor deposition. The molecules of the inducing layer nucleate into lamellar grains from the edge to the channel, resulting in a good morphological contact to the bottom electrodes. The following active layer maintains nearly layer-by-layer growth mode and yields uniformed terraced-like films both on the electrode edges and in the channels. With the inducing layer, pentacene thin-film bottom-contact transistors are obtained with a hole mobility exceeding 1 cm2 V−1 s−1.

Two-dimensional chirality transfer from self-assembled (SA) molecules to covalently bonded products was achieved via on-surface synthesis on Au(111) substrates by choosing 1,4-dibromo-2,5-didodecylbenzene (12DB) and 1,4-dibromo-2,5-ditridecylbenzene (13DB) as designed precursors. Scanning tunneling microscopy investigations reveal that their aryl–aryl coupling reaction occurs by connecting the nearest neighboring precursors and thus preserving the SA lamellar structure. The SA structures of 12(13)DB precursors determine the final structures of produced oligo-p-phenylenes (OPP) on the surface. Pure homochiral domains (12DB) give rise to homochiral domains of OPP, whereas lamellae containing mixed chiral geometry of the precursor (13DB) results in the formation of racemic lamellae of OPP.

One of the most charming and challenging topics in organic chemistry is the selective C–H bond activation. The difficulty arises not only from the relatively large bond-dissociation enthalpy, but also from the poor reaction selectivity. In this work, Au(111) and Ag(111) surfaces were used to address ortho C–H functionalization and ortho-ortho couplings of phenol derivatives. More importantly, the competition between dehydrogenation and deoxygenation drove the diversity of reaction pathways of phenols on surfaces, that is, diselective ortho C–H bond activation on Au(111) surfaces and monoselective ortho C–H bond activation on Ag(111) surfaces. The mechanism of this unprecedented phenomenon was extensively explored by scanning tunneling microscopy, density function theory, and X-ray photoelectron spectroscopy. Our findings provide new pathways for surface-assisted organic synthesis via the mono/diselective C–H bond activation.

A series of organic field-effect transistors (OFETs) with patterned ultra-thin films for NH3 detection are achieved via fast dip-coating. The morphology and packing structure of the ultra-thin films are greatly dependent on the surface energy of the substrates, geometry features of the patterned electrodes and evaporation atmosphere during the dip-coating process, which in turn results in a significant difference in the NH3 sensing properties. Based on the newly proposed mechanism, low-trap dielectric-semiconductor interfaces, a stripe-like morphology and an ultrathin film (as low as 2 nm) enable the OFET-based sensors to exhibit unprecedented sensitivity (∼160) with a short response/recovery time. The efficient (2 mm s−1), reliable, and scalable patterning strategy opens a new route for solution-processed OFET-based gas sensors.

The design of multinuclear metal complexes requires a match of the ligand-to-metal vectors and the preferred coordination geometries of the metal ions. Only a few ligands are known with a parallel orientation of N→M vectors that brings the metal ions into close proximity. We establish here the adenine derivative 1,N6-ethenoadenine (εA) as an ideal bis(monodentate) ligand. Scanning tunneling microscope images of alkylated εA on graphite surface clearly indicate that these ligands bind to Ag(I) ions. The molecular structures of [Ag2(1)2](ClO4)2 and [Ag2(2)2](ClO4)2 (1, 9-ethyl-1,N6-ethenoadenine; 2, 9-propyl-1,N6-propylenoadenine) confirm that dinuclear complexes with short Ag···Ag distances are formed (3.0256(3) and 2.984(1) Å, respectively). The structural motif can be extended to divalent metal ions, as was shown by determining the molecular structure of [Cu2(1)2(CHO2)2(OH2)2](NO3)2·2H2O with a Cu···Cu distance of 3.162(2) Å. Moreover, when introducing the 1,N6-ethenoadenine deoxyribonucleoside into parallel-stranded DNA duplexes, even dinuclear Ag(I)-mediated base pairs are formed, featuring the same transoid orientation of the glycosidic bonds as the model complexes. Hence, 1,N6-ethenoadenine and its derivatives are ideally suited as bis(monodentate) ligands with a parallel alignment of the N→M vectors for the construction of supramolecular metal complexes that require two metal ions at close distance.

•The bulk heterojunctions (BHJs) in all-polymer solar cells are studied by KPFM.•The phase segregations of the BHJs are quantitatively characterized.•KPFM results under illumination are attributed to the photo-generated charge behaviors.•Inner structures of the BHJs are extrapolated by studying the charge behaviors.Photo-generated charge behaviors in the bulk heterojunctions (BHJs) of all-polymer solar cells (PSCs) are studied by Kelvin probe force microscopy (KPFM). Root-mean-square deviations (RMSDs, Rq) of the contact potential difference (CPD) images are applied to quantitatively characterize the phase segregations of the BHJs. When the BHJs are illuminated, CPD values and Rq of CPD images are changed, which attributes to the photo-generated charge transfer and accumulation. Inner structures of the BHJ are thus extrapolated by studying the charge behaviors, demonstrating KPFM an effective technique to study the relationship between inner structures and photovoltaic activities in all-PSCs.

•A bottom-up in-situ polymerization strategy is utilized to produce the surface-grafting PPY electrodes.•The patterned PPY electrodes may serve as good electrode to efficiently drive organic complementary inverters.•The inverter with PPY electrodes exhibits an operation frequency of several kHz.Surface-grafting conducting polymer has advantage to circumvent the difficulty in patterning as well as the weak interface adhesion on substrate of the conventional conducting polymer, which would be desirable for its application as electrodes in electronic devices. In this work, the patterned surface-grafting polypyrrole (PPY) is used as electrode, which shows merits such as strong interface adhesion, robustness against solvent treatment, easy scaling-up, and good conductivity. Remarkably, the surface-grafting PPY electrodes can efficiently drive both p-type and n-type organic field-effect transistors. By combining p-/n-type transistors, organic complementary inverters are constructed with PPY electrodes, which exhibit low operational voltage (<8 V), high gain (6–17), and low power dissipation (several tens of nW). The switching voltage is approximately 0.5Vdd with a high noise margin (>70% of 0.5Vdd). Dynamic switching measurements indicate that the inverter has an operational frequency of about 3.3 kHz. This is the first report on kilohertz organic complementary inverter driven with surface-grafting conducting polymer electrodes. High device performance, together with the facile patternability and other merits, may promote the application of surface-grafting conducting polymer electrode in the field of organic electronics.Organic complementary inverters driven by surface-grafting conducting polypyrrole electrodes are demonstrated. The inverters show a high operation frequency of about 3.3 kHz, low operational voltage (<8 V), high gain (6–17), low power dissipation (several tens of nW), and large noise margin (>70% ½ Vdd). This work may promote the application of surface-grafting conducting polymer electrode in organic electronics.

The growth of organic semiconductor with controllable morphology is a crucial issue for achieving high-performance devices. Here we present the systematic study of the effect of the alkyl chain attached to the functional entity on controlling the growth of oriented microcrystals by dip-coating. Alkylated DTBDT-based molecules with variable chain lengths from n-butyl to n-dodecyl formed into one-dimensional micro- or nanostripe crystals at different pulling speeds. The alignment and ordering are significantly varied with alkyl chain length, as is the transistor performance. Highly uniform oriented and higher-molecular-order crystalline stripes with improved field-effect mobility can be achieved with an alkyl-chain length of around 6. We attribute this effect to the alkyl-chain-length-dependent packing, solubility, and self-assembly behavior.

Surface-supported coupling reactions between 1,3,5-tris(4-formylphenyl)benzene and aromatic amines have been investigated on Au(111) using scanning tunneling microscopy under ultra-high-vacuum conditions. Upon annealing to moderate temperatures, various products, involving the discrete oligomers and the surface covalent organic frameworks, are obtained through thermal-triggered on-surface chemical reactions. We conclude from the systematic experiments that the stoichiometric composition of the reactants is vital to the surface reaction products, which is rarely reported so far. With this knowledge, we have successfully prepared two-dimensional covalently bonded networks by optimizing the stoichiometric proportions of the reaction precursors.Keywords: aldehyde−amine coupling; on-surface chemistry; scanning tunneling microscopy; stoichiometric ratio; two-dimensional framework

Gas sensors, as useful tools to detect specific gas species such as toxic and explosive gases or volatile organic compounds, are the key components for environmental monitoring, fruit maturity and food safety monitoring, health care, and so on. The present commercial products based on porous metal oxide materials still face problems, such as high temperature operation and low level of selectivity. Thin films or nanostructures of organic materials with thickness or grain size down to nanometer scale represent promising candidates for gas sensing due to their potential for achieving high selectivity, portability and low cost. However, there are still challenges related to their stability, reproducibility and response/recovery speed despite the efforts in materials design, morphology control or device configuration, all of which have been expended during the last few decades. In this review, we summarize the progress of recent research on gas sensors based on organic ultra-thin films and nanostructures. We specifically discuss the effect of microstructure in the active layer on the sensing performance and mechanism.

The narrowest armchair graphene nanoribbon (AGNR) with five carbons across the width of the GNR (5-AGNR) was synthesized on Au(111) surfaces via sequential dehalogenation processes in a mild condition by using 1,4,5,8-tetrabromonaphthalene as the molecular precursor. Gold-organic hybrids were observed by using high-resolution scanning tunneling microscopy and considered as intermediate states upon AGNR formation. Scanning tunneling spectroscopy reveals an unexpectedly large band gap of Δ = 2.8 ± 0.1 eV on Au(111) surface which can be interpreted by the hybridization of the surface states and the molecular states of the 5-AGNR.

The formation of additional phenyl rings on surfaces is of particular interest because it allows for the building-up of surface covalent organic frameworks. In this work, we show for the first time that the cyclotrimerization of acetyls to aromatics provides a promising approach to 2D conjugated covalent networks on surfaces under ultrahigh vacuum. With the aid of scanning tunneling microscopy, we have systematically studied the reaction pathways and the products. With the combination of density functional theory calculations and X-ray photoemission spectroscopy, the surface-assisted reaction mechanism, which is different from that in solution, was explored.

We report a new strategy to directly attach Au nanoparticles onto YAG:Ce3+ phosphor via a chemical preparation method, which yields efficient and quality conversion of blue to yellow light in the presence of a low amount of phosphor. Photoluminescent intensity and quantum yield of YAG:Ce3+ phosphor are significantly enhanced after Au nanoparticle modification, which can be attributed to the strongly enhanced local surface electromagnetic field of Au nanoparticles on the phosphor particle surface. The CIE color coordinates shifted from the blue light (0.23, 0.23) to the white light region (0.30, 0.33) with a CCT value of 6601 K and a good white light CRI value of 78, which indicates that Au nanoparticles greatly improve the conversion efficiency of low amounts of YAG:Ce3+ in WLEDs.

We present here a study on the electrical conduction properties of individual polypyrrole nanobelts by using conductive atomic force microscopy and discuss a general effect while probing soft materials. A length-dependent analysis demonstrates that the tip could induce local defects into the polymer structure and, thus diminishes the electrical conduction.

The distribution of polarized space charges and their relaxation behavior in high dielectric constant electric conductor/polymer composites are main factors that determine the frequency-dependent dielectric constant and dielectric loss. However, few reports focus on this motif. We present here the dielectric performance and mechanism of a unique kind of composites with multi-layers (coded as [MWCNT/EP]x, where x refers to the number of layers), fabricated by using layer-by-layer casting technique. Each composite layer with same thickness was composed of multi-walled carbon nanotubes (MWCNTs) and epoxy (EP) resin. When the loading of MWCNTs is 0.5 wt%, the four-layer [MWCNT0.5/EP]4 material shows the highest dielectric constant (465 at 1 Hz) and low dielectric loss tangent (0.7 at 1 Hz), about 4 and 2.1 × 10−2 times the values of traditional MWCNT0.5/EP composite, respectively. By investigating the space charge polarization (SCP), Debye polarization and dielectric moduli in [MWCNT/EP]x materials, the complex relationships and the origin among dielectric constant, dielectric loss, frequency and the content of filler were clearly elucidated. The SCP within each layer is different from that between layers. The greatly improved dielectric properties of [MWCNT/EP]x materials are believed to be the reinforced SCP and blocked transport of carriers between every two layers.

•Fast dip-coating was firstly used to fabricate patterned organic transistors.•Ultrathin oriented microstripes were obtained on hydrophobic surfaces.•Area-selective behaviour of organic films can be finely controlled.•Patterned transistor exhibit reasonable field-effect characteristics.Oriented organic field-effect transistor (OFET) stripe arrays on hydrophobic substrates were fabricated by fast dip-coating technique. The addressable growth was achieved by decreasing surface energy of the channel areas with respect to the electrodes via hydrophobic treatment. The higher surface energy of the electrodes allows solution to adhere and then organic semiconductors nucleate and bridge the channels after evaporation of the solvent. Area-selective behaviour can be controlled by adjusting surface property of transistor channel, geometry features of the gold electrodes, pulling speed and evaporation atmosphere. The mechanism behind is the competition between receding of the solution and evaporating of the solvent that generate the organic semiconductor films on the substrate. The patterned bottom-contact transistor arrays exhibit carrier mobility of 2.0 × 10−3 cm2 V−1 s−1, while no field-effect characteristics can be detected for bottom-contact arrays without hydrophobic treatment. Such reliable, fast and solution-based patterned OFET arrays are highly desirable for large-scale and low-cost production.

Increased interest in wearable and smart electronics is driving numerous research works on organic electronics. The control of film growth and patterning is of great importance when targeting high-performance organic semiconductor devices. In this Feature Article, we summarize our recent work focusing on the growth, crystallization, and device operation of organic semiconductors intermediated by ultrathin organic films (in most cases, only a monolayer). The site-selective growth, modified crystallization and morphology, and improved device performance of organic semiconductor films are demonstrated with the help of the inducing layers, including patterned and uniform Langmuir–Blodgett monolayers, crystalline ultrathin organic films, and self-assembled polymer brush films. The introduction of the inducing layers could dramatically change the diffusion of the organic semiconductors on the surface and the interactions between the active layer with the inducing layer, leading to improved aggregation/crystallization behavior and device performance.

The ability to assemble NPs into ordered structures that are expected to yield collective physical or chemical properties has afforded new and exciting opportunities in the field of nanotechnology. Among the various configurations of nanoparticle assemblies, two-dimensional (2D) NP patterns and one-dimensional (1D) NP arrays on surfaces are regarded as the ideal assembly configurations for many technological devices, for example, solar cells, magnetic memory, switching devices, and sensing devices, due to their unique transport phenomena and the cooperative properties of NPs in assemblies. To realize the potential applications of NP assemblies, especially in nanodevice-related applications, certain key issues must still be resolved, for example, ordering and alignment, manipulating and positioning in nanodevices, and multicomponent or hierarchical structures of NP assemblies for device integration. Additionally, the assembly of NPs with high precision and high levels of integration and uniformity for devices with scaled-down dimensions has become a key and challenging issue.Two-dimensional NP patterns and 1D NP arrays are obtained using traditional lithography techniques (top-down strategies) or interfacial assembly techniques (bottom-up strategies). However, a formidable challenge that persists is the controllable assembly of NPs in desired locations over large areas with high precision and high levels of integration. The difficulty of this assembly is due to the low efficiency of small features over large areas in lithography techniques or the inevitable structural defects that occur during the assembly process. The combination of self-assembly strategies with existing nanofabrication techniques could potentially provide effective and distinctive solutions for fabricating NPs with precise position control and high resolution. Furthermore, the synergistic combination of spatially mediated interactions between nanoparticles and prestructures on surfaces may play an increasingly important role in the controllable assembly of NPs.In this Account, we summarize our approaches and progress in fabricating spatially confined assemblies of NPs that allow for the positioning of NPs with high resolution and considerable throughput. The spatially selective assembly of NPs at the desired location can be achieved by various mechanisms, such as, a controlled dewetting process, electrostatically mediated assembly of particles, and confined deposition and growth of NPs. Three nanofabrication techniques used to produce prepatterns on a substrate are summarized: the Langmuir–Blodgett (LB) patterning technique, e-beam lithography (EBL), and nanoimprint lithography (NPL). The particle density, particle size, or interparticle distance in NP assemblies strongly depends on the geometric parameters of the template structure due to spatial confinement. In addition, with smart design template structures, multiplexed NPs can be assembled into a defined structure, thus demonstrating the structural and functional complexity required for highly integrated and multifunction applications.

In this communication, a direct coupling of patterned growth of rubrene crystalline thin films with OFET fabrication is presented. The film was grown between pre-patterned Au electrodes covered with an organic monolayer, which directly allowed the fabrication of OFET devices with a sub-micrometer channel length. More importantly, close packed and porous film structures can be controlled by adjusting the space between the electrodes, resulting in a two orders of magnitude difference in carrier mobility. The technique is completely compatible with lithography methods thus may find potential applications in addressable and crosstalk suppressing OFET arrays.

In this communication, a direct coupling of patterned growth of rubrene crystalline thin films with OFET fabrication is presented. The film was grown between pre-patterned Au electrodes covered with an organic monolayer, which directly allowed the fabrication of OFET devices with a sub-micrometer channel length. More importantly, close packed and porous film structures can be controlled by adjusting the space between the electrodes, resulting in a two orders of magnitude difference in carrier mobility. The technique is completely compatible with lithography methods thus may find potential applications in addressable and crosstalk suppressing OFET arrays.

Post-annealing was conducted to investigate the control efficiency of template-directed growth of organic molecules. Disordered organic patterns can be converted to ordered ones via elimination of randomly distributed molecular islands by annealing, resulting in full control of organic molecules on templates with tunable spacing. Molecular dynamics (MD) simulations revealed that the strong interaction between the molecule and the template plays a key role in tuning the control efficiency. With this method, direct growth of multicolor patterns is demonstrated.