Perylenetetracarboxylic Diimide Research Articles

Layer-by-layer approach for fabricating organic/inorganic hybrid multilayers based on a polyoxyethylene-substituted perylenetetracarboxylic diimide and CdS

An amphiphilic perylenetetracarboxylic diimide derivative (APDI) is designed and synthesized. The highly ordered APDI/CdS hybrid film was obtained successfully via a novel layer-by-layer approach by using a simple H2S-vapor annealing over each layer of APDI/Cd2+ Langmuir-Shäfer film fabricated from Langmuir monolayer of APDI molecules formed on the surface of CdCl2 aqueous solution. Examination by spectroscopic methods revealed APDI molecules in the hybrid film adopt a typical H aggregation mode whereas those in pure film adopt a slipped co-facial stacking mode in an “edge-on” conformation. The wurtzite CdS nanoparticles have been incorporated successfully into APDI matrix. The film morphology changed obviously from elongated domains of ca. 70nm in length in pure APDI film to small nanoparticles of ca. 55nm in diameter in APDI/CdS hybrid film. In particular, energy transfer from CdS to APDI has been established in the hybrid film.

Spontaneous Wetting Dynamics in Perylene Diimide n-Type Thin Films Deposited at Room Temperature by Supersonic Molecular Beam

During the last few years, the perylene tetracarboxylic diimide derivative PDIF-CN2 has been identified as one of the most interesting compounds to achieve air-stable n-type organic thin-film transistors. In this work, a detailed investigation on the properties of PDIF-CN2 thin films deposited by supersonic molecular beam deposition technique on HMDS-treated Si/SiO2 surfaces is reported. Our efforts have been addressed to analyze deeply the role played by the growth rate (R) on the thin film properties, working with the substrates kept at room temperature and using a kinetic energy of the impinging molecules of about 17 eV. In this way, we could observe that while, just after the deposition, the layers were not compact, being composed of small and mostly separated islands with a rate-dependent density, an unconventional spreading effect of the condensate took place over time until the formation of a continuous film. According to our results, this spontaneous wetting process occurs over very long time scal...

Optical and Self-Assembly studies of some New Perylene Tetracarboxylic Diimides

Optical and Self-Assembly studies of some New Perylene Tetracarboxylic Diimides

Room temperature homeotropic alignment of mixed-stacking columns of H6TP donors and PDI acceptors by charge transfer interactions and size match

Room temperature mesophases were achieved by blending donors 2,3,6,7,10,11-hexakis-(hexyloxy)-triphenylene (H6TP) with acceptors N,N′-bis(1-heptyloctyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) via charge transfer interactions and size match. Compared with H6TP (mesophase temperature range: 97°C–51°C) and PDI (119°C–108°C), H6TP/PDI=1/2 (138°C - room temperature), 1/1 (139°C–40°C) and 1/0.5 (130°C–31°C) blends showed increase of clearing points and decrease of crystallization temperatures with wide mesophase temperature ranges. Different from edge-on orientation of PDI and no preferred alignment of H6TP, face-on alignments of all mixtures films could be achieved and stable at room temperature by cooling from isotropic state. It was inferred that stabilised columnar mesophases of H6TP/PDI blends were caused by charge transfer (CT) interactions and size match of them in hexagonal columnar phases. The existence of CT interactions was demonstrated by upfield shifts of aromatic protons in the 1H NMR spectra of H6TP/PDI blends solutions and obvious fluorescent quenching in the blends films.

Persistent Photoconductivity in Perylene Diimide Nanofiber Materials

Perylene tetracarboxylic diimide (PTCDI) derivatives have been extensively investigated for one-dimensional (1D) self-assembly and their applications in optoelectronic devices. Our study on self-assembled PTCDI nanofiber materials revealed a persistent photoconductivity (PPC) effect, which is sustained conductivity after illumination is terminated. A comprehensive understanding of the PPC effect in PTCDI nanofibril materials will enable us to explore and enhance their optoelectronic applications. Here, we have investigated the PPC effect in the nanofibers assembled from 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI) with respect to the PPC relaxation at different temperatures, illumination power densities, molar amount, and morphology of the PTCDI film deposited on the interdigitated electrodes. The photocurrent relaxation was also performed on several other PTCDI nanofiber materials for comparative study. We conclude that the significant PPC effect in MP-PTCDI nanofibers can b...

Single-Molecule Charge Transport and Electrochemical Gating in Redox-Active Perylene Diimide Junctions

A series of redox-active perylene tetracarboxylic diimide (PTCDI) derivatives have been synthesized and studied by electrochemical cyclic voltammetry and electrochemical scanning tunnelling microscopy break junction techniques. These PTCDI molecules feature the substitution of pyrrolidine at the bay (1,7-) position of perylene and are named pyrrolidine-PTCDIs. These moieties exhibit a small bandgap (2.1 eV) compared with the “normal” (unsubstituted) PTCDI molecule (2.5 eV). Pyrrolidine-PTCDIs were functionalized with different anchoring groups (thiol, amine, pyridine) for building metal–molecule–metal (m–M–m) junctions. The single-molecule conductance values of pyrrolidine-PTCDIs have been determined by analyzing a large number of molecular (m–M–m) junctions created between an STM tip and substrate using a statistical method. Furthermore, we studied the gate dependence of the single-molecule conductance by trapping a molecule between the two electrodes and recording the current as a function of electroche...

Synergetic Solvent Engineering of Film Nanomorphology to Enhance Planar Perylene Diimide-Based Organic Photovoltaics.

Solvent additive has proven as a useful protocol for improving the film nanomorphology of polymer donor (D): fullerene acceptor (A) blends in bulk heterojunction (BHJ) photovoltaic cells. By contrast, the effect of such solvent additive on nonfullerene BHJ cells based on perylene diimide acceptor, for instance, is less effective because of their highly planar structure and strong π-aggregation in solid state. Here we choose N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) and thieno[3,4-b]thiophene-alt-benzodithiophene (PTB7) as a model D:A blend system to investigate how solvent engineering strategy synergistically impacts the blend film nanomorphology. Based on the differences of solvent volatility and solubility, various host solvents-chloroform (CF) and chlorobenzene (CB) and solvent additives-chloronaphthalene (CN) and 1,8-diiodooctane (DIO) are selected for comparative studies. It is found that the π-aggregation of PDIs can be largely suppressed by using low-boiling point (Tb) CF solvent, yet enlarged by using high-Tb CB. Moreover, CN additive provides good solubility of PDI molecules and hence reduces large PDI aggregates in CB system, while DIO exhibiting poor solubility works oppositely. By contrast, DIO that presents larger Tb difference with CF prolongs the film-forming, which assists in optimizing the PDI aggregation and increases the intermixed PTB7:PDI phases more significantly than CN in CF system, yielding the finest phase-separation morphology and balanced charge mobility. Consequently, the inverted BHJ cells based on CF-processed PTB7:PDI blend film with 0.4 vol % DIO exhibit the highest PCE of 3.55% with a fill factor of 56%, both of which are among the best performance for such a paradigm PTB7:PDI blend-based BHJ cells.

Supramolecular 3,4:9,10-perylenetetracarboxylic diimide triads containing moieties of sumanene polyphenol derivative: Synthesis and photochemical transformations

A polyphenol derivative of the sumanene-containing triad with a central perylenetetracarboxylic diimide moiety was synthesized via several consecutive chemical transformations of N,N'-bis(3',5'-dimethoxybenzyl)-1,7-bis[4''-(N,N'-disumanenyl)aminophenyl]perylene-3,4:9,10-tetracarboxylic diimide. The phenolic hydroxyl groups of the resulting derivative were partly protected by introduction of two different protective groups, pentaspiran and tert-butyl butyrate ones. It was shown that this modified derivative can be used to obtain a promising positive-tone photoresists with high parameters for extreme ultraviolet nanolithography on exposure to light at 13.5 nm for the manufacture of 20 to 16 nanometer chips.

Chemical Self-Doping of Organic Nanoribbons for High Conductivity and Potential Application as Chemiresistive Sensor.

Intrinsically low electrical conductivity of organic semiconductors hinders their further development into practical electronic devices. Herein, we report on an efficient chemical self-doping to increase the conductivity through one-dimensional stacking arrangement of electron donor-acceptor (D-A) molecules. The D-A molecule employed was a 1-methylpiperidine-substituted perylene tetracarboxylic diimide (MP-PTCDI), of which the methylpiperidine moiety is a strong electron donor, and can form a charge transfer complex with PTCDI (acting as the acceptor), generating anionic radical of PTCDI as evidenced in molecular solutions. Upon self-assembling into nanoribbons through columnar π-π stacking, the intermolecular charge transfer interaction between methylpiperidine and PTCDI would be enhanced, and the electrons generated are delocalized along the π-π stacking of PTCDIs, leading to enhancement in conductivity. The conductive fiber materials thus produced can potentially be used as chemiresistive sensor for vapor detection of electron deficient chemicals such as hydrogen peroxide, taking advantage of the large surface area of nanofibers. As a major component of improvised explosives, hydrogen peroxide remains a critical signature chemical for public safety screening and monitoring.

Real roles of perylenetetracarboxylic diimide for enhancing photocatalytic H2-production

On account of the steps of water splitting reaction, suppression of the electron–hole recombination is one key factor to improve the photocatalytic activity. Composites with π-conjugated molecules are promising to inhibit the recombination process by delocalization of the photo-generated electron. In this study, we synthesized perylenetetracarboxylic diimide (PDI) decorated Zn0.5Cd0.5S hybrid photocatalysts to reveal the function of the PDI in promoting the charge separation by electron transfer process. To understand the mechanisms that govern the carrier separation, transport, extraction and their recombination within this inorganic/organic nanocomposite, three PDIs, namely PDI-1, PDI-2 and PDI-3 with different molecular structure were loaded in the Zn0.5Cd0.5S, respectively, and were investigated comparatively. It is demonstrated that PDIs play great roles in increasing the specific surface area and stabilizing the photogenerated electron–hole pairs, resulting in enhancement of the overall hydrogen production rate. The highest rate of 1.32mmolh−1g−1 was achieved on the Zn0.5Cd0.5S-PDI-1 composite, which is 6 times higher than the pristine Zn0.5Cd0.5S, owning to the effective photo-driven electron transport between the Zn0.5Cd0.5S and the PDI-1. The results of the current work are relevant in understanding the nature of charge-transfer pathways in photoinduced catalysis.

Synthesis, characterization and photovoltaic performance of novel glass-forming perylenediimide derivatives

Novel glass-forming perylene-3,4,9,10-tetracarboxylic diimide (PDI) derivatives were synthesized from 1,7-dibromoperylene-3,4,9,10-tetracarboxylic diimides by nucleophilic substitution with a glass-forming mexylaminotriazine unit, characterized, and their performance as electron acceptors in bulk heterojunction photovoltaic cells with P3HT as donor were studied. Imide groups (octyl and 2,6-diisopropylphenyl) and bay substituents (bromo or pyrrolidinyl) were used to study the impact of sterics and electronics on device performance. The HOMO and LUMO levels of the materials were determined using cyclic voltammetry. The morphology and packing behavior of molecules in films of blends with P3HT were studied using Atomic Force Microscopy and X-ray diffraction, and in all four cases, the PDI derivatives remain in the amorphous phase, while the P3HT portion of the blends crystallizes. The devices gave photovoltaic performances ranging from 0.2 to 0.6%, and while the bay substituents showed negligible impact on device performance, switching from bulky 2,6-diisopropylphenyl imide groups to linear octyl chains improved the efficiency of the devices by 36%, current density by 66% and fill factor by 16%. The performances observed for devices incorporating these PDI glasses are comparable to that of devices with crystalline PDI acceptors.

Surface Decorating of CH₃NH₃PbBr₃ Nanoparticles with the Chemically Adsorbed Perylenetetracarboxylic Diimide.

An organic dye-modified organolead halide CH3NH3PbBr3 nanoparticle (cubic) is prepared successfully by using a perylenetetracarboxylic diimide (PDI) bearing an -NH3(+) headgroup as the capping ligand. The nanopartilces are homogeneous with high crystallinity. The photoluminescence of perovskite is quenched completely by the chemically adsorbed PDI molecules. This efficient fluorescence quenching has confirmed that the PDI molecules are anchored on the surface of CH3NH3PbBr3 nanoparticle. The resulting nanoparticles can be dispersed in organic solvents, and the resulting dispersion remains stable for days. This result provides a general guideline for surface engineering of organolead halide CH3NH3PbBr3 nanoparticles.

Facile fabrication of organic/inorganic nanotube heterojunction arrays for enhanced photoelectrochemical water splitting.

Organic/inorganic heterojunction photoanodes are appealing for making concurrent use of the highly photoactive organic semiconductors, and the efficient dielectric screening provided by their inorganic counterparts. In the present work, organic/inorganic nanotube heterojunction arrays composed of TiO2 nanotube arrays and a semiconducting N,N-(dicyclohexyl) perylene-3,4,9,10-tetracarboxylic diimide (PDi) layer were fabricated for photoelectrochemical water splitting. In this arrayed architecture, a PDi layer with a tunable thickness was coated on anodic TiO2 nanotube arrays by physical vapor deposition, which is advantageous for the formation of a uniform layer and an adequate interface contact between PDi and TiO2. The obtained PDi/TiO2 junction exhibited broadened visible light absorption, and an effective interface for enhanced photogenerated electron-hole separation, which is supported by the reduced charge transfer resistance and prolonged excitation lifetime via impedance spectroscopy analysis and fluorescence emission decay investigations. Consequently, such a heterojunction photoanode was photoresponsive to a wide visible light region of 400-600 nm, and thus demonstrated a highly enhanced photocurrent density at 1.23 V vs. a reversible hydrogen electrode. Additionally, the durability of such a photoanode can be guaranteed after long-time illumination because of the geometrical restraint imposed by the PDi aggregates. These results pave the way to discover new organic/inorganic assemblies for high-performance photoelectric applications and device integration.

Photophysical Properties of Perylenetetracarboxylic Diimide Dimers with Slipped “Face-to-Face” Stacked Structure and Different Bay Substitutions

A series of perylenetetracarboxylic diimides (PDIs) dimers with slipped “face-to-face” stacked structure and different substituents at the bay positions have been synthesized and the molecular structures are characterized by 1H NMR, MALDI-TOF and elemental analysis. And different substituents at the bay positions of the PDI ring bring about various steric hindrances. These different steric hindrances have caused significant differences on the absorption and emission spectra. The correlation between the photophysical properties and the molecular structure is discussed.

Length-dependent thermal transport in one-dimensional self-assembly of planar π-conjugated molecules.

This work reports a thermal transport study in quasi-one-dimensional organic nanostructures self-assembled from conjugated planar molecules via π-π interactions. Thermal resistances of single crystalline copper phthalocyanine (CuPc) and perylenetetracarboxylic diimide (PTCDI) nanoribbons are measured via a suspended thermal bridge method. We experimentally observed the deviation from the linear length dependence for the thermal resistance of single crystalline β-phase CuPc nanoribbons, indicating possible subdiffusion thermal transport. Interestingly, a gradual transition to the linear length dependence is observed with the increase of the lateral dimensions of CuPc nanoribbons. The measured thermal resistance of single crystalline CuPc nanoribbons shows an increasing trend with temperature. However, the trend of temperature dependence of thermal resistance is reversed after electron irradiation, i.e., decreasing with temperature, indicating that the single crystalline CuPc nanoribbons become 'amorphous'. Similar behavior is also observed for PTCDI nanoribbons after electron irradiation, proving that the electron beam can induce amorphization of single crystalline self-assembled nanostructures of planar π-conjugated molecules. The measured thermal resistance of the 'amorphous' CuPc nanoribbon demonstrates a roughly linear dependence on the nanoribbon length, suggesting that normal diffusion dominates thermal transport.

High performance nitrogen dioxide sensor based on organic field-effect transistor utilizing ultrathin CuPc/PTCDI-C8 heterojunction

Organic field-effect transistors (OFETs) with a heterojunction structure, consisting of the p-type and n-type organic semiconducting materials of copper phthalocyanine (CuPc) and the dioctyl perylene tetracarboxylic diimide (PTCDI-C8), respectively, were fabricated. The heterojunction OFETs were used as the nitrogen dioxide (NO2) gas sensors, and the sensing properties were characterized with the variation of PTCDI-C8 layer thicknesses. The results showed that the OFET sensors with the optimized film thickness of 0.5nm PTCDI-C8 and 7nm CuPc, had one order of magnitude enhancement of sensitivity, compared to the device with single CuPc active layer. The sensitivity improvement was attributed to the intensification of the charge transfer in the heterojunction structure while introducing the oxidizing gas of NO2.

Optical and Electrical Properties of New Perylene Diimide Thin Films

Perylene diimides with high photosensitivity and high electron mobility have attracted much attention for use in organic semiconductor devices. In this investigation, thin films of six new perylene tetracarboxylic diimides (PTCDI) were fabricated by spin coating, on glass as substrate, and their optical and electrical properties were studied. The absorption spectra of thin films of PTCDI furnished more informative bands than those of the compounds in solution. The morphology of the thin films was examined by scanning electron microscopy and x-ray diffraction. The absorption spectra and I–V characteristics of the compounds were affected by their molecular structures. HOMO–LUMO band gaps of the films were in the range 1.9–2.0 eV. Band gaps calculated by use of computational methods were comparable with experimental results.

Solution-processed single-crystal perylene diimide transistors with high electron mobility

We have successfully demonstrated a single-crystal field-effect transistors (FETs) based on an asymmetric perylenetetracarboxylic diimide (a-PDI) compound with polystyrene (PS)/SiO2 bilayer as gate dielectric. The single crystals are in-situ grown on substrate from simple solution evaporation method, thus may be suitable for large area electronics applications. The PS modified gate dielectric could minimize charge trapping by the hydroxyl groups of the SiO2 surface. The resulting solution processed single crystals transistors are characterized in ambient air, and exhibited maximum electron mobility of ca. 1.2cm2V−1s−1 and high Ion:Ioff>105.

Enhancement of visible-light-driven photocatalytic H2 evolution from water over g-C3N4 through combination with perylene diimide aggregates

Graphitic carbon nitride (g-C3N4) is among the most promising metal-free photocatalysts for H2 production from solar-driven water reduction. However, the photocatalytic efficiency of bulk g-C3N4 powders is limited. In this work, molecular aggregates of perylene tetracarboxylic diimides (PTCDIs, a robust class of air-stable n-type organic semiconductor) were loaded via solution processing on the surface of g-C3N4, which is pre-deposited with cocatalyst Pt nanoparticles. The PTCDIs/Pt/g-C3N4 composites thus fabricated exhibit broader visible-light response than Pt/g-C3N4, and possess excellent photochemical stability. The initial intramolecular charge transfer features of the PTCDIs, as well as their energy levels being matched to g-C3N4, ensure subsequent charge separation in the PTCDIs/Pt/g-C3N4 composites. When the composites are dispersed into aqueous solutions containing triethanolamine as a sacrificial electron donor, a tenfold enhancement of H2 evolution activity (∼0.375μmolh−1) is achieved compared to bare Pt/g-C3N4 under visible-light (λ≥420nm) irradiation.

Pn-Heterojunction effects of perylene tetracarboxylic diimide derivatives on pentacene field-effect transistor.

We investigated the heterojunction effects of perylene tetracarboxylic diimide (PTCDI) derivatives on the pentacene-based field-effect transistors (FETs). Three PTCDI derivatives with different substituents were deposited onto pentacene layers and served as charge transfer dopants. The deposited PTCDI layer, which had a nominal thickness of a few layers, formed discontinuous patches on the pentacene layers and dramatically enhanced the hole mobility in the pentacene FET. Among the three PTCDI molecules tested, the octyl-substituted PTCDI, PTCDI-C8, provided the most efficient hole-doping characteristics (p-type) relative to the fluorophenyl-substituted PTCDIs, 4-FPEPTC and 2,4-FPEPTC. The organic heterojunction and doping characteristics were systematically investigated using atomic force microscopy, 2D grazing incidence X-ray diffraction studies, and ultraviolet photoelectron spectroscopy. PTCDI-C8, bearing octyl substituents, grew laterally on the pentacene layer (2D growth), whereas 2,4-FPEPTC, with fluorophenyl substituents, underwent 3D growth. The different growth modes resulted in different contact areas and relative orientations between the pentacene and PTCDI molecules, which significantly affected the doping efficiency of the deposited adlayer. The differences between the growth modes and the thin-film microstructures in the different PTCDI patches were attributed to a mismatch between the surface energies of the patches and the underlying pentacene layer. The film-morphology-dependent doping effects observed here offer practical guidelines for achieving more effective charge transfer doping in thin-film transistors.