Perylenetetracarboxylic Diimide Research Articles

Multimode simulation of dimer absorption spectra from first principles calculations: Application to the 3,4,9,10-perylenetetracarboxylic diimide dimer

First principles calculations based on density functional theory (DFT) have been combined with the multimode vibronic theory of coupled identical monomers to simulate the absorption spectra of dimers. In comparison to our previous study [J. Guthmuller et al., J. Chem. Theory Comput. 4, 2094 (2008)], where the vibrational excitations strictly accompany the electronic excitations, the vibronic model has been generalized so that the vibronic basis set contains vibrational excitations for both the ground and the excited electronic states. As a matter of illustration, this approach has been applied to a perylenetetracarboxylic diimide dimer employing a fixed dimer geometry. The exciton coupling energy is evaluated with time dependent DFT and random phase approximation calculations and by describing the effects of the solvent with the polarizable continuum model. First, the simulated monomer absorption spectrum is found to be in excellent agreement with experiment. Then, the simulated dimer absorption spectrum presents a strong dependency on the exciton coupling energy and on the inclusion of ground state vibrational excitations in the basis set. It is further shown that considering only fundamental vibrational excitations for the ground electronic state provides almost converged spectra and can therefore be used as a good first approximation. Moreover, the comparison with experiment demonstrates that the dimer absorption spectrum can be successfully reproduced by employing the exciton coupling energy determined at the time dependent DFT level provided that the effects of the solvent are included.

A new donor–acceptor double‐cable carbazole polymer with perylene bisimide pendant group: Synthesis, electrochemical, and photovoltaic properties

AbstractWe report here electrochemical synthesis of novel soluble donor–acceptor (D–A) polymer with suitably functionalized perylenetetracarboxylic diimide dye derivative covalently linked to carbazole moiety (Cbz‐PDI). The band gap, Eg was measured using UV–Vis spectroscopy and compared with that obtained by cyclic voltammetry (CV). Efficient intramolecular electron transfer from carbazole‐donor to perynediimide‐acceptor leads to remarkable fluorescence quenching of the perylene core. Furthermore, spectroelectrochemical property and surface morphology of the polymer film were investigated. Characteristic monoanion and dianion radical bands on the UV–Vis absorption spectra attributed to the electrochemical reduction of the neutral polymer were observed. During the reduction process, red color of the film turned into blue and violet, respectively. Finally, the photovoltaic performance of the D–A double‐cable polymer was checked and nearly 0.1% electrical conversion efficiency is obtained under simulated AM 1.5 solar light with 100 mW/cm2 radiation power. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6280–6291, 2009

Synthesis and quantum chemical study of PDI derivatives with phenylalkynyl groups at the bay position

Six new perylenetetracarboxylic diimide (PDI) compounds were prepared by introducing alkynyl or alkynylphenyl groups with different length to the bay position of PDI ring. The UV–vis absorption and emission spectra of these new compounds were recorded. The red-shift on the maximum absorption and emission peaks revealed the efficient participation of the side conjugation chain to the whole conjugation system. The molecular structure, the frontier molecular orbital and the energy gaps between the highest occupied orbital (HOMO) and the lowest un-occupied orbital (LUMO) were calculated with DFT method. The results show good consistent with the experimental results. The absorption and emission spectra of these six compounds were also simulated with TD-B3lyp/6-31g(d) and TD-PBE1PBE/6-31g(d) methods. The simulated results for the compounds with short side conjugation chain show better response to the experimental results. However, the quantum calculation on the compounds with long conjugated side chain do not give satisfied results because of the significant electron transfer characteristics in the excited states.

Low-voltage organic n-channel thin-film transistors based on a core-cyanated perylene tetracarboxylic diimide derivative

Using the small-molecule organic semiconductor bis(1 H,1 H-perfluorobutyl)-dicyano-perylene tetracarboxylic diimide, C 3F 7CH 2-PTCDI-(CN) 2, and a low-temperature-processed, high-capacitance gate dielectric based on a phosphonic acid self-assembled monolayer, we have manufactured n-channel thin-film transistors on glass substrates. The transistors operate with low voltages (2 V) and have an electron mobility of 0.04 cm 2/Vs and an on/off ratio of 10 5. By combining C 3F 7CH 2-PTCDI-(CN) 2 n-channel transistors with pentacene p-channel transistors, we have also manufactured low-voltage, low-power organic complementary inverters with good static and dynamic performance.

Organic Thin-Film Solar Cells Using Electron-Donating Perylene Tetracarboxylic Acid Derivatives

Various electron-donating amino groups were introduced into the perylene core of perylene tetracarboxylic acid derivatives (PTCs) to address the potential use in organic solar cells. Broad absorptions of the PTC solutions in the visible to near-infrared (NIR) region suggest that PTCs are promising light-harvesting molecules for solar cells. Electrochemical measurements reveal that the introduction of the electron-donating amino groups makes the energy level of the highest occupied molecular orbital (HOMO) shallow, imparting electron-rich characteristics to the PTCs. The electronic properties of the PTCs are studied on the basis of quantum chemical calculations. The results show that the variation of the amino groups has a significant influence on the HOMO level, while the lowest unoccupied molecular orbital (LUMO) level is relatively sensitive to the electronegativity of the PTC terminal atoms. The PTC thin films exhibit broad absorption bands in the visible to NIR region, as for the PTC solutions, and possess relatively shallow HOMO and LUMO energies that are higher or comparable to those of fullerene C60. These excellent properties encouraged us to employ amine-substituted PTCs as electron donors in a thin film solar cell with C60 as an n-type semiconductor. Photovoltaic devices with a structure of indium tin oxide (ITO)/PTCs/C60/bathocuproine (BCP)/Al were fabricated by spin-coating PTCs on an ITO electrode. The devices with perylene tetracarboxylic acid diimides (PTCDIs), bearing highly basic amino groups (Py-PTCDI, Me2N-PTCDI, and Ph2N-PTCDI), exhibit the higher power conversion efficiencies than those with carbazoyl PTCDI (Cz-PTCDI) and perylene tetracarboxylic acid dianhydrides (PTCDAs). The higher device performance originates from the efficient electron transfer from the PTCs to C60 as the results of the relatively shallow HOMO and LUMO levels of the PTCs bearing the highly basic amino groups. The dependence of the device performance on the PTC film thickness indicates that the introduction of diphenylamino groups on the perylene core suppresses the nonradiative decay of the exciton without decreasing the hole mobility. These results will provide important information for the molecular design of post PTC derivatives.

Effect of molecular packing on interfacial recombination of organic solar cells based on palladium phthalocyanine and perylene derivatives

Planar heterojunction solar cells made of three different perylene tetracarboxylic diimide (PTCDI) derivatives as acceptor and palladium phthalocyanine as donor are demonstrated. Electron-hole pair recombination at donor/acceptor interface was compared for three PTCDI derivative solar cells by optical modeling and the effect of molecular packing of the PTCDI derivatives on charge dissociation is discussed. We observed that PTCDI with hexyl chains has the highest charge separation efficiency among three PTCDI derivatives, leading to a power conversion efficiency of 2.0% in solar cells.

Highly Polarized and Self-Waveguided Emission from Single-Crystalline Organic Nanobelts

Well-defined single-crystalline nanobelts with strong fluorescence were fabricated from a perylene tetracarboxylic diimide molecule modified with specific side-chains that afford flip-flap stacking, rather than the common translated stacking, between the molecules along the long axis of the nanobelt. The nanobelts thus fabricated possess highly polarized, self-waveguided emission, making them ideal candidates for application in nanolasers and other angle-dependent optical nanodevices.

Fluorescent Silica Nanoparticles by Silylation

Shining nanosil: Fluorescent trimethoxysilanes were prepared by the hydrosilylation of N-allyl perylene tetracarboxylic diimides and used for the covalent grafting of silica and silica nanoparticles (see picture). The fluorescent chromophores operate independently at the surface of these particles.

Template-Directed Molecular Nanostructures on the Ag/Pt(111) Dislocation Network

We report on the high effectiveness of the Ag/Pt(111) dislocation network template for guiding the formation of well-ordered perylenetetracarboxylic diimide (PTCDI) molecular nanostructures due to its laterally strong inhomogeneous properties. Numerous PTCDI nanostructures show chiral arrangements driven by specific substrate−molecule and molecule−molecule interactions, with a higher strength coming from the substrate, which, per molecule, is quantified by simulations to be at least in the same order as a hydrogen bond.

The electrical and dielectrical behavior of n-conducting perylene tetracarboxylic diimide derivatives

A comparison of the electrical characteristics of organic field-effect transistors (OFETs) based on derivatives of the electron-conductor perylene tetracarboxylic diimide (PTCDI) in top-contact configuration is presented. The derivatives used are N,N′-dimethyl-3,4,9,10-perylene-tetracarboxylic-diimide (DiMe-PTCDI), N,N′-diphenyl-3,4,9,10-perylene-tetracarboxylic-diimide (DiPhenyl-PTCDI), N,N′-dimethoxyethyl-3,4,9,10-perylene-tetracarboxylic-diimide (DiMethoxyethyl-PTCDI), N,N′-di(3-pentyl)-3,4,9,10-perylene-tetracarboxylic-diimide (Di3Pentyl-PTCDI), and N,N′-diheptyl-3,4,9,10-perylene-tetracarboxylic-diimide (DiHeptyl-PTCDI). Current/voltage measurements were first performed in situ and later ex situ. Additionally, the effect of annealing and bias stress was probed in situ. A strong influence of the different side groups on the order of magnitude of the electron mobility is revealed, ranging from 4×10−6 cm2/V s for DiMethoxyethyl-PTCDI to 5×10−2 cm2/V s for DiHeptyl-PTCDI. While none of the devices was stable in air after exposition to air, only the DiMe-PTCDI one resumed its functionality after restoring vacuum conditions. The dielectric functions of the derivatives was derived, additionally revealing optical isotropy for all films and varying surface roughness. While DiHeptyl-PTCDI and Di3Pentyl-PTCDI, yielding also the highest electron mobilities, form smooth layers with negligible surface roughness, strong island formation was be observed for DiPhenyl-PTCDI and DiMethoxyethyl-PTCDI, yielding low mobilities. This island growth was also confirmed by atomic force microscopy measurements. Ageing of the samples for several months under ambient conditions leads to increased roughness for the very rough samples. Layers with smooth surface, on the other hand, showed no significant change in the dielectric behavior of the sample.

Chlorination: A General Route toward Electron Transport in Organic Semiconductors

We show that adding chlorine atoms to conjugated cores is a general, effective route toward the design of n-type air-stable organic semiconductors. We find this to be true for acenes, phthalocyanines, and perylene tetracarboxylic diimide (PDI)-based molecules. This general finding opens new avenues in the design and synthesis of organic semiconductors. We compared a series of fluoro- and chloro-functionalized acenes, phthalocyanines, and PDI-based molecules. The acenes synthesized showed high and balanced ambipolar transport in the top-contact organic field effect transistor (OFET) geometry. The electron-withdrawing halogen groups lowered the LUMO and the charge injection barrier for electrons, such that electron and hole transport occurred simultaneously. If the chlorine added does not distort the planarity of the conjugated core, we found that the chloro-functionalized molecules tend to have a slightly smaller HOMO-LUMO gap and a lower LUMO level than the fluoro-containing molecules, both from calculations and cyclic voltammetry measurements in solution. This is most likely due to the fact that Cl contains empty 3d orbitals that can accept pi-electrons from the conjugated core, while F does not have energetically accessible empty orbitals for such delocalization.

Entrapment of Decanethiol in a Hydrogen-Bonded Bimolecular Template

We have used scanning tunneling microscopy to investigate the deposition of 1-decanethiol onto a bimolecular self-assembled network composed of PTCDI (perylene tetracarboxylic diimide) and melamine on a Au(111) surface. A new laterally organized phase in which the pores of a parallelogram bimolecular arrangement trap two decanethiol molecules is identified. Disruption of the hexagonal PTCDI-melamine network arrangement after decanethiol deposition is also observed, providing insights about the interplay between supramolecular and substrate-adsorbate interactions.

Effects of Photoinduced Electron Transfer on the Rational Design of Molecular Fluorescence Switch

Aiming at exploring the relationship between the spacer and fluorescence switch properties, we synthesized a series of new photoactive triads, in which one perylenetetracarboxylic diimide unit acting as the electron acceptor was attached to two ferrocene moieties through different spacers. This kind of donor-spacer-acceptor structure allows for tuning one of the key factors that governs photoinduced electron transfer, the distance between the electron donor and acceptor units. The excited-state electron-transfer processes were monitored by both steady-state and time-resolved emission as well as transient absorption techniques. It was found that fluorescence intensity of the solution of all triads 1-3 can be reversibly modulated by the electrochemical oxidation and reduction sequentially. More importantly, as the length of the spacer between the donor and acceptor increases, the background fluorescence increased proportionally, but the contrast ratio of the fluorescence decreases. Together these two factors determine the assay sensitivity, and therefore this work is helpful to provide a basis for the rational design of fluorescence switch by optimizing these factors above.

Role of a phthalocyanine–fullerene dyad in multilayered organic solar cells

A double-bridged phthalocyanine–fullerene dyad (H 2Pc–C 60ee) was used as photo-active intramolecular donor–acceptor system in a layered organic solar cell. In this device, a poly(3-hexylthiophene) (PHT) film was used as electron donor, whereas either C 60 or perylene tetracarboxylic diimide (PTCDI) film was selected as electron acceptor. The introduction of the dyad layer leads to an enhancement of the power conversion efficiency ( η ) in all the examples, mainly due to an increase of the open-circuit voltage. By introducing the dyad in PTCDI-containing cells, the efficiency (being 0.32%) was enhanced by almost three times compared to that of the reference (0.12%). In C 60-containing cells, the efficiency of the dyad sample (being 0.30%) was over one and half times higher than that of the reference in the absence of the dyad (0.18%). The role of such a dyad in the solar cells is discussed in detail.

Ultraviolet photoelectron spectroscopy of pristine poly (sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate) (PTEBS) and doped with perylene tetracarboxylicdiimide (PTCDI) nanobelts

AbstractWe investigated the possibility of doping poly (sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate) (PTEBS) with perylene tetracarboxylicdiimide (PTCDI) nanobelts through ultraviolet photoelectron spectroscopy (UPS) measurements. For our experiment, PTEBS was tuned to absorb maximum light in the range of 450 nm to 550 nm which corresponds to the maximum solar irradiance of the Earth’s atmosphere. Nanobelts of PTCDI were synthesized by gas phase self assembly process. Doping PTEBS with PTCDI nanobelts causes a shift in the Fermi level of the composite material with respect to the vacuum level as observed in the photoemission spectrum. With increased PTCDI doping, PTCDI does not act much like an electron donor, but more like an electron acceptor. The peaks corresponding to the sigma bonds shift towards the vacuum level with higher concentrations of the dopant. Using angled resolved photoemission spectra from a 3m toroidal grating monochromator, PTEBS displays change in the highest occupied molecular orbital in respect to its Fermi level when the side groups were substituted by H+ or OH- groups. The results confirm that the binding energy decreases with increase in activity of the dissolved hydrogen ions. It is evident that there is an increase in the density of states near the Fermi level and shifts to lower binding energies of the occupied molecular orbitals with pH level decrease, which is in agreement with the published optical absorption characteristics of PTEBS. Since UPS data confirm that PTCDI nanobelts dope PTEBS, along with its tunable absorption characteristics, this composite might be a promising material for optoelectronic application.

Accurate and Simultaneous Determination of Carrier Density and Mobility in Organic Semi-conducting Materials

AbstractHow to accurately determine carrier mobility and density in organic semiconducting materials is a very important subject for their optoelectronic applications including light-emitting diodes, solar cells, and thin film field-effect transistors. In this work, we report on a unique data analysis procedure for space-charge limited currents to simultaneously obtain the carrier density and mobility in semiconducting organic-materials. This procedure has been used for a few newly synthesized perylene tetracarboxylic diimide (PDI) derivatives with tunable π-stack structures without altering the electronic characteristic of individual molecules. How π-stack structural variation and residual carrier density affect electron transport performance will be discussed.

Fluorescence Quenching in a Perylenetetracarboxylic Diimide Trimer

A perylenetetracarboxylic diimide (PDI) trimer (3) linked by a triazine ring has been prepared. The UV-vis absorption spectra together with the (1)H NMR spectra revealed that two of the three PDI subunits in the trimer presents a face-to-face stacked configuration while the third one appended acts as a monomer. There is no strong interaction between the dimer and monomer at ground state. However, the fluorescence of the monomer was quenched efficiently by the dimer. The transient absorption and excitation spectra of this compound suggest that the energy transfer from the excited states of monomer to an excimer like state of dimer is responsible for this quick and efficient fluorescence quenching. The rate of the energy transfer is comparable to that from B800 to B850 in LH2.

Supramolecular self-assembly study of a flexible perylenetetracarboxylic diimide dimer in Langmuir and Langmuir–Blodgett films

A novel perylenetetracarboxylic diimide molecule ( 2PDI-TAZ), which contains two perylenetetracarboxylic diimide (PDI) attached to a melamine headgroup, was designed and synthesized. Supramolecular self-assemblies were studied in Langmuir and Langmuir–Blodgett films. Surface pressure–area isotherm measurements and the spectroscopic studies indicate that the 2PDI-TAZ molecules adopted a face-to-face configuration and edge-on orientation in Langmuir or the multilayer LB films. The presence of the barbituric acid in subphase change the hydrophilicity of 2PDI-TAZ due to the hydrogen bonding between melamine and barbituric acid, which has been revealed by the π – A isotherms and the FT-IR spectra. Transmission electron microscopy images of the LB films deposited from the barbituric acid solution revealed uniform nanowire morphology while the X-ray diffraction studies indicate that the molecules in the solid film packed with high order. The strong excimer emission of 2PDI-TAZ in LB films suggests enforced face-to-face configuration for the PDI unites in LB films in relative to that in solution.

Intermolecular Interactions of Perylene diimides in Photovoltaic Blends of Fluorene Copolymers: Disorder Effects on Photophysical Properties, Film Morphology and Device Efficiency

AbstractIn the present work, we correlate the photophysical and photovoltaic properties with the respective film morphologies of three different blends made of the fluorene copolymers poly(9,9′‐dioctylfluorene‐co‐benzothiadiazole) (F8BT), poly[9,9′‐dioctylfluorene‐co‐N‐(4‐butylphenyl)diphenylamine] (TFB), and poly[9,9′‐dioctyfluorene‐co‐bis‐N,N′‐(4‐butylphenyl)‐bis‐N,N‐phenyl‐1,4‐phenylenediamine] (PFB) when blended with a perylene tetracarboxylic diimide (PDI) derivative. Additional photophysical studies in reference PDI blends of the electronically inert poly(styrene) matrix address the enhanced PDI intermolecular solid‐state interactions. We resolve the process of resonance energy transfer from excited polymer hosts to PDI and the process of photoinduced hole transfer from PDI to the polymer hosts. We deduce the efficiency of charge‐transfer PDI photoluminescence (PL) quenching and we discuss the power‐law PL kinetics seen in the as‐spun systems. Next we determine the dependence of the device external quantum efficiency (EQE) of these blends, in a range of annealing temperatures and PDI loadings. Differential scanning calorimetry enables precise selection of annealing temperatures. Optical microscopy shows that annealing enhances the order characteristics in the PDI aggregates in the F8BT:PDI system. In the case of the TFB:PDI and PFB:PDI blends, AFM studies suggest the formation of PDI‐rich domains on the film/air interface. The degree of order in the π–π stacking of the PDI monomers is inferred by the UV–Vis and PL spectra of the blends. The extent of order characteristics in PDI aggregates is correlated with the thermal properties of the hosts that control PDI molecular mobility upon annealing. The efficient dispersion of disrupted PDI crystallites is proposed to form appropriate percolation networks that favor balanced extraction of photogenerated carriers.

Synthesis and characterization of the first soluble nonracemic chiral main-chain perylene tetracarboxylic diimide polymers

The first two nonracemic chiral main-chain perylene tetracarboxylic diimide (PDI) polymers have been synthesized via acyclic diene metathesis polymerization. The use of optically pure l-α amino acids as the starting materials enables us to tune PDI π-stacking interaction in optically active polymers. The integration of π-stack tuning groups renders two main-chain PDI polymers soluble in chloroform. Spectroscopic evidences suggest that PDI π-stacks form in chloroform solutions of the two PDI polymers, even at very low concentration, probably via an intra-molecular folding process. Inside π-stacks, PDI units organize in a left-handed helical fashion. Flexible free-standing films can be cast from chloroform solution of one polymer.