Tetracarboxylic Diimide Research Articles

One-Pot Synthesis of Stable NIR Tetracene Diimides via Double Cross-Coupling

Tetracene tetracarboxylic diimides have been synthesized based on direct double ring extension of electron-deficient naphthalene diimides involving metallacyclopentadienes. Atomic structure and electronic transitions responsible for their NIR absorption spectra are investigated with quantum-chemical calculations. In light of their unique structure and admirable photophysical and electronic properties, this new molecular skeleton is promising candidate for n-type semiconductors.

High‐Mobility Air‐Stable Solution‐Shear‐Processed n‐Channel Organic Transistors Based on Core‐Chlorinated Naphthalene Diimides

AbstractHigh charge carrier mobility solution‐processed n‐channel organic thin‐film transistors (OTFTs) based on core‐chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are demonstrated. These OTFTs were prepared through a solution shearing method. Core‐chlorination of NDIs not only increases the electron mobilities of OTFTs, but also enhances their air stability, since the chlorination in the NDI core lowers the lowest unoccupied molecular orbital (LUMO) levels. The air‐stability of dichlorinated NDI was better than that of the tetrachlorinated NDIs, presumably due to the fact that dichlorinated NDIs have a denser packing of the fluoroalkyl chains and less grain boundaries on the surface, reducing the invasion pathway of ambient oxygen and moisture. The devices of dichlorinated NDIs exhibit good OTFT performance, even after storage in air for one and a half months. Charge transport anisotropy is observed from the dichlorinated NDI. A dichlorinated NDI with −CH2C3F7 side chains reveals high mobilities of up to 0.22 and 0.57 cm2 V−1 s−1 in parallel and perpendicular direction, respectively, with regard to the shearing direction. This mobility anisotropy is related to the grain morphology. In addition, we find that the solution‐shearing deposition affects the molecular orientation in the crystalline thin films and lowers the d(001)‐spacing (the out‐of‐plane interlayer spacing), compared to the vapor‐deposited thin films. Core‐chlorinated NDI derivatives are found to be highly suitable for n‐channel active materials in low‐cost solution‐processed organic electronics.

BODIPY-Based Donor–Acceptor π-Conjugated Alternating Copolymers

Four novel π-conjugated copolymers incorporating 4,4-difluoro-4-borata-3a-azonia-4a-aza-s-indacene (BODIPY) core as the “donor” and quinoxaline (Qx), 2,1,3-benzothiadiazole (BzT), N,N′-di(2′-ethyl)hexyl-3,4,7,8-naphthalenetetracarboxylic diimide (NDI), and N,N′-di(2′-ethyl)hexyl-3,4,9,10-perylene tetracarboxylic diimide (PDI) as acceptors were designed and synthesized via Sonogashira polymerization. The polymers were characterized by 1H NMR spectroscopy, gel permeation chromatography (GPC), UV–vis absorption spectroscopy, and cyclic voltammetry. Density functional theory (DFT) calculations were performed on polymer repeat units, and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were estimated from the optimized geometry using B3LYP functional and 6-311g(d,p) basis set. Copolymers with Qx and BzT possessed HOMO and LUMO energy levels comparable to those of BODIPY homopolymer, while PDI stabilized both HOMO and LUMO levels. Semiconductor behav...

Single-molecule switching with non-contact atomic force microscopy

We report upon controlled switching of a single 3,4,9,10-perylene tetracarboxylic diimide derivative moleculeon a rutile TiO2(110) surface using a non-contact atomic force microscope at room temperature. Aftersubmonolayer deposition, the molecules adsorb tilted on the bridging oxygen row.Individual molecules can be manipulated by the atomic force microscope tip in awell-controlled manner. The molecules are switched from one side of the rowto the other using a simple approach, taking benefit of the sample tilt and thetopography of the titania substrate. From density functional theory investigationswe obtain the adsorption energies of different positions of the molecule. Theseadsorption energies are in very good agreement with our experimental observations.

Room‐Temperature Phase Demixing in Bulk Heterojunction Layers of Solution‐Processed Organic Photodetectors: the Effect of Active Layer Ageing on the Device Electro‐optical Properties

AbstractHerein, we address the reduction in the external quantum efficiency (EQE) of solution‐processed organic photodetectors caused by the room temperature phase demixing of components in the composite material of the photoactive layer. The reduction takes place under ambient conditions and after the completion of device fabrication. As a model system, we study photoactive blend films that consist of the electron acceptor N,N’‐bis(alkyl)‐3,4,9,10‐perylene tetracarboxylic diimide) (PDI) and the electron donor polymer poly(9,9’‐dioctylfluorene‐co‐benzothiadiazole) (F8BT). The ambient ageing of these photo­active layers is a consequence of the PDI component segregation; however, the final PDI domain size remains smaller than the resolution limit of optical microscopy. We find that the photophysical properties of the aged F8BT:PDI layer and the EQE of the aged device are significantly altered. The fabrication of F8BT:PDI layers from solvents of increasing boiling point allows for the spectroscopic monitoring of the ageing‐induced phase segregation (a‐PSG) process. For each solvent used, the extent of a‐PSG is correlated with the PDI dispersion in the F8BT matrix as received immediately after layer deposition. The tendency for room temperature phase demixing becomes stronger as PDI is more finely dispersed in the freshly spun F8BT:PDI layer. The evolution of the room temperature phase segregation of PDI has a negative impact on the photophysical processes that are essential for charge photogeneration in the F8BT:PDI photoactive layer.

Multi‐Electron‐Acceptor Dyad and Triad Systems Based on Perylene Bisimides and Fullerenes

Fullerene (C(60)) and 3,4,9,10-perylene tetracarboxylic diimide (PTDCI) were used as building blocks for an electron acceptor dyad (C(60)-PTCDI) and triad (C(60)-PTCDI-C(60)). As the first reduction potentials for C(60) and PTCDI are very close, simultaneous introduction of two or three electrons is possible into the dyad and triad, respectively. Further stepwise electrochemical reduction leads to formation of a series of well-defined anionic species in which electrons associated with the fullerene or the PTDCI components of the molecule can be clearly distinguished. In total, up to four electrons can be reversibly injected into the dyad C(60)-PTCDI and up to six into the triad C(60)-PTCDI-C(60) system. The optical absorption properties in the UV/Vis range are also crucially defined by the distribution of electrons between the acceptor parts, as the injection/removal of electrons causes drastic colour changes in the dyad and the triad systems.

In situ vacuum measurement of the thickness dependence of electron mobility in naphthalenetetracarboxylic diimide-based field-effect transistors

We present an in situ electrical measurement for the characteristics of n-channel organic field-effect transistors (OFETs) based on N,N′-dipentadecafluorooctyl-1,4,5,8-naphtalene tetracarboxylic diimide (NTCDI-C8F15) organic semiconductors. The field-effect mobilities have been estimated as a function of the number of monolayers (MLs). The electron mobility (μe) of NTCDI-C8F15 OFET as thin as 2 ML has been determined. μe increases rapidly with increasing film thickness, although it reaches saturation thickness (d0) around 3.5 ML. Atomic force microscopy confirms island mode growth mechanism of NTCDI-C8F15 with near upright position stacking on SiO2 substrate and it is attributed to the fluorophobic effect of the material.

Photocatalytic degradation of rhodamine B by dye-sensitized TiO2 under visible-light irradiation

Perylene tetracarboxylic diimide (PTCDI), widely used in organic photovoltaic devices, is an n-type semiconductor with strong absorption in the visible-light spectrum. There has been almost no study of the PTCDI-sensitized TiO2 composite used to photocatalytically degrade pollutants. In this study, PTCDI- and copper phthalocyanine tetrasulfonic acid (CuPcTs)-sensitized TiO2 composites were prepared using a hydrothermal method. The morphologies and structures of the two composites were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible spectroscopy, and fluorescence spectroscopy. The visible-light photocatalytic activities of the composites were evaluated using the degradation of rhodamine B as a model reaction. Results showed that dye-sensitized TiO2 samples had a wider absorption spectrum range and higher visible-light photocatalytic activity compared to TiO2 samples. The double dye-sensitized (or co-sensitized) TiO2 composite with efficient electron collection exhibited higher photocatalytic activity than did the single dye-sensitized TiO2 composite. The electron transfer processes of single and double dye-sensitized TiO2 composites were illustrated according to band theory.

A theoretical discussion on the relationships among molecular packings, intermolecular interactions, and electron transport properties for naphthalene tetracarboxylic diimide derivatives

Three naphthalene tetracarboxylic diimide derivatives 1–3 with high electron mobilities and long-term ambient stabilities were investigated employing Marcus–Levich–Jortner formalism at the density functional theory (DFT) level. The complicated relationships among molecular packings, intermolecular interactions, and transport properties for these compounds were focused on and analyzed through investigating the sensitivities of transfer integrals to intermolecular relative orientations, the optimizations of the major transport pathways and the calculations of intermolecular interaction energies by using dispersion-corrected DFT. The results show that the transfer integrals are sensitive to the subtle changes of relative orientations of molecules, especially for core-chlorinated compounds, and there is an interplay between intermolecular interaction and molecular packing. It is found that the transfer integrals associated with the molecular packing motifs of these systems determine their electron mobilities. Interestingly, further discussions on band structures, the anisotropies and temperature dependences of mobilities, and the comparisons of mobilities before and after optimization indicate that the intermolecular packing motifs in the film state may be different from those in the crystalline state for 2. Finally, we hope that our conjecture would facilitate the future design and preparation of high-performance charge-transport materials.

Naphthalene and perylene diimides for organic transistors

The development of ambient stable organic n-channel semiconductor molecules for thin-film transistors has experienced a tremendous impetus in the last decade to close the gap in performance in comparison to that of their p-channel counterparts. Especially naphthalene and perylene tetracarboxylic diimides (NDI and PDI) have shown to be the most valuable building blocks to achieve this challenging goal and to gain insight into the molecular structure-transistor performance relationship. Remaining challenges and new emerging research fields for these n-type semiconductors are the optimization of their deposition on flexible substrates, the control of their long term ambient stability and their implementation in complementary transistor circuits, display and sensor devices.

Molecular Design and Synthetic Approaches to Electron-Transporting Organic Transistor Semiconductors

This review covers the various classes of molecular structures that may be used as the basis for the synthesis of organic semiconductors that favor electron transport in field-effect transistors and related electronic and optoelectronic devices. The types of compounds include tetracarboxylic diimides, heterocyclic oligomers, fullerenes, and metal complexes. Approaches to polymers are also mentioned. Although brief discussions of transistor operation and applications are included, the emphasis is on the rationale for choosing these structures, and synthetic routes to them. Performance of exemplary compounds in transistors is also discussed.

Structural and property comparison between the di‐piperidinyl‐ and di‐pyrrolidinyl‐substituted perylene tetracarboxylic diimides

AbstractFour compounds 1–4 connected with cyclic amino groups at the bay positions of perylenetetracarboxylic diimide (PDI) have been prepared and the isomers with 1,7‐ and 1,6‐substituted PDIs were successfully separated by conventional column chromatography. The structures of 1,7‐dipyrrolidinyl‐substituted PDI (1) and 1,7‐dipiperidinyl‐substituted PDI (3) were further characterized by single crystal X‐ray diffraction experiments. The crystal structure revealed that the small difference in the molecular structure has caused significant difference on the absorption and emission spectra as well as the electrochemical properties. The shorter bond length of C1N3, together with the more sp2 hybrid atomic orbital characteristics of the nitrogen atom in pyrrolidine relative to those in piperidine is found to be responsible for this large property difference between 1 and 3. Copyright © 2010 John Wiley & Sons, Ltd.

The Dependence of Device Dark Current on the Active‐Layer Morphology of Solution‐Processed Organic Photodetectors

AbstractOrganic photodiodes are presented that utilize solution‐processed perylene diimide bulk heterojunctions as the device photoactive layer. The polymer (9,9′‐dioctylfluorene‐co‐benzothiadiazole; F8BT) is used as the electron donor and the N,N′‐bis(1‐ethylpropyl)‐3,4,9,10‐perylene tetracarboxylic diimide (PDI) derivative is used as the electron acceptor. The thickness‐dependent study of the main device parameters, namely of the external quantum efficiency (EQE), the short‐circuit current (ISC), the open‐circuit voltage (VOC), the fill factor (FF), and the dark current (ID) is presented. In as‐spun F8BT:PDI devices the short‐circuit EQE reaches the maximum of 17% and the VOC value is as high as 0.8 V. Device ID is in the nA mm−2 regime and it correlates with the topography of the F8BT:PDI layer. For a range of annealing temperatures ID is monitored as the morphology of the photoactive layer changes. The changes in the morphology of the photoactive layer are monitored via atomic force microscopy. The thermally induced coalescence of the PDI domains assists the dark conductivity of the device. ID values as low as 80 pA mm−2 are achieved with a corresponding EQE of 9%, when an electron‐blocking layer (EB) is used in bilayer EB/F8BT:PDI devices. Electron injection from the hole‐collecting electrode to the F8BT:PDI medium is hindered by the use of the EB layer. The temperature dependence of the ID value of the as‐spun F8BT:PDI device is studied in the range of 296–216 K. In combination with the thickness and the composition dependence of ID, the determined activation energy Ea suggests a two‐step mechanism of ID generation; a temperature‐independent step of electric‐field‐assisted carrier injection from the device contacts to the active‐layer medium and a thermally activated step of carrier transport across the device electrodes, via the PDI domains of the photoactive layer. Moreover, device ID is found to be sensitive to environmental factors.

Self‐Sorted Assembly in a Mixture of Donor and Acceptor Chromophores

A simple and novel supramolecular approach for orthogonal self-assembly of donor and acceptor chromophores has been demonstrated. Suitably designed 1,5-dialkoxynaphthalene (DAN) and naphthalene tetracarboxylic acid diimide (NDI) derivatives were used as the donor and acceptor systems, respectively. The molecular design for self-sorting relies upon the precise control over the placement of the self-complementary hydrogen-bonding units (amide functionality) with respect to the individual chromophore. By design, the distances between the two amide groups in the donor and acceptor chromophores are not identical, and consequently the effect of the hydrogen-bonding interaction cannot be maximised in the case of alternate donor-acceptor-type pi-stacking. Thus a relatively weak charge-transfer interaction is expected to be sacrificed, and segregated assembly among the individual chromophores should be enforced by virtue of the much stronger effects of hydrogen bonding and pi-pi stacking. Detailed spectroscopic studies were carried out to probe the mode of self-assembly in various derivatives of the DAN-NDI donor-acceptor pairs to establish the utility of the molecular design as a generalised one for orthogonal self-assembly.

Synthesis and Evaluation of New Spacers for Use as dsDNA End-Caps

A series of aliphatic and aromatic spacer molecules designed to cap the ends of DNA duplexes have been synthesized. The spacers were converted into dimethoxytrityl-protected phosphoramidites as synthons for oligonucleotides synthesis. The effect of the spacers on the stability of short DNA duplexes was assessed by melting temperature studies. End-caps containing amide groups were found to be less stabilizing than the hexaethylene glycol spacer. End-caps containing either a terthiophene or a naphthalene tetracarboxylic acid diimide were found to be significantly more stabilizing. The former showed a preference for stacking above an A*T base pair. Spacers containing only methylene (-CH(2)-) and amide (-CONH-) groups interact weakly with DNA and consequently may be optimal for applications that require minimal influence on DNA structure but require a way to hold the ends of double-stranded DNA together.

High‐Performance Air‐Stable n‐Type Organic Transistors Based on Core‐Chlorinated Naphthalene Tetracarboxylic Diimides

AbstractCore‐chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n‐channel organic thin‐film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge‐transport behavior is investigated in terms of structure–property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close π‐plane distance (3.3–3.4 Å), a large π‐stack overlap (slipping angle ca. 62°), and high crystal densities (2.046–2.091 g cm−3). These features result in excellent field‐effect mobilities of up to 1.43 cm2 V−1 s−1 with minimal hysteresis and high on–off ratios (ca. 107) in air. This is similar to the highest n‐channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip‐stacked face‐to‐face packing with an interplanar distance of around 3.4 Å, resulting in a high mobility (up to 0.44 cm2 V−1 s−1). The air‐stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)‐treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics.

Investigation of electron trapping behavior in n-channel organic thin-film transistors with ultrathin polymer passivation on SiO 2 gate insulator

Electron trapping behavior at the interface between N, N′-ditridecyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C13) film and thermal SiO 2 was investigated by utilizing ultrathin poly(methyl methacrylate) (PMMA) gate passivation layers. From the capacitance–voltage analysis for the PTCDI-C13/PMMA/SiO 2 interface, it is found that the electron tunneling appeared with PMMA thinner than 0.8 nm, and that the thickness of the gate passivation layer should be at least 1 nm for preventing injection-type hysteresis in the capacitance–voltage curve. The effective electron mobility of organic thin-film transistors (OTFTs) based on PTCDI-C13 with SiO 2 gate insulator was increased by suppressing shallow-level interface traps on SiO 2 with the PMMA layer, which can be partially accounted for by the multiple trap and release model. In this work, the thickness and the density of the PMMA layers were precisely controlled with a simple spin-coating process. Even 1.3-nm thick PMMA layer caused the improvements of the electron mobility and the air stability of the n-channel conduction.

Highly emissive metal—organic framework composites by host—guest chemistry

The unique host-guest chemistry of metal-organic frameworks (MOFs) can be used to implement additional properties by loading the cavities with functional molecules or even nanoparticles. We describe the gas-phase loading of MOFs featuring either a three-dimensional (MOF-5, MOF-177 and UMCM-1) or one-dimensional channel system (MIL-53(Al)) with the highly emissive perylene derivative N,N-bis(2,6-dimethylphenyl)-3,4:9,10-perylene tetracarboxylic diimide (DXP) or an iridium complex, (2-carboxypyridyl)bis(3,5-difluoro-2-(2-pyridyl)phenyl)iridium(III) (FIrpic). The resulting host-guest composites show strong luminescence, with their optical properties being dominated by the guest species. DXP-loaded MOFs exhibit a high stability towards guest displacement by solvent molecules, while the interaction of FIrpic with the host is weaker. The emissive properties of intercalated DXP also indicate host-guest interactions such as caging effects, strong quenching of the MOF host emission, as well as aggregate formation.

Photoresponsive n-channel organic field effect transistor based on naphthalene bis-benzimidazole with divinyltetramethyl disiloxane-bis (benzo-cyclobutene) gate insulator

A novel photoresponsive organic field effect transistor (photOFET) based on naphthalene bis-benzimidazole (NBBI) by employing a transparent divinyltetramethyl disiloxane-bi (BCB) as dielectric is presented. The optical properties of naphthalene tetracarboxylic diimide (NTCDI) were changed by substitution of imidazole groups, in order to improve amplification of fabricated transistor by light in the visible region. The electrical characteristics of photOFET showed n-channel properties under illumination and dark. The NBBI based organic field effect transistor exhibited saturated electron mobility of 6 × 10 −3 cm 2/V s with threshold voltage of 7.2 V. The photogenerated charge carriers strongly influence the drain-source current in comparison to dark condition. The photosensitivity and photoresponsivity of device are found to be 93.4 mA/W and 14.3 mA/W, respectively, at off-state of device under white light at AM 1.5 condition.

Fabrication of aligned microwire arrays of perylene bisimide by micromolding in capillary

In this work, we synthesized a novel perylene tetracarboxylic acid diimides derivative (APBI-G) which shows a strong self-assembling tendency to the semiconducting nano/microwires based on the augmented intermolecular hydrogen bonding interaction. We demonstrate the spinning of continuous thread of APBI-G from the liquid–liquid interface and also the fabrication of patterned nano/microwire arrays using MIMIC (micromolding in capillaries) method. MIMIC-fabricated APBI-G nano/microwires showed the excellent uniaxial orientation, large birefringence, and reproducible electrical conductivity (1.93 ± 0.47 × 10 −6 S cm −1).