Perylenetetracarboxylic Diimide Research Articles

Exciton Delocalization and Polarizability in Perylenetetracarboxylic Diimide Probed Using Electroabsorption and Fluorescence Spectroscopies

Perylenetetracarboxylic diimide (PTCDI) is an n-type organic semiconductor molecule that has been widely utilized in numerous applications such as photocatalysis and field-effect transistors. Polarizability and dipole moment, which are inherent properties of molecules, are important parameters that determine their responses to external electric and optical fields, physical properties, and reactivity. These parameters are fundamentally important for the design of innovative materials. In this study, the effects of external electric fields on absorption and fluorescence spectra were investigated to obtain the PTCDI parameters. The PTCDI substituted by an octyl group (N,N′-Dioctyl-3,4,9,10-perylenedicarboximide) dispersed in a polymethyl methacrylate (PMMA) matrix was studied in this work. The features of vibronic progression in the absorption spectrum were analogous to those observed in solution. The red shift of the absorption band caused by the Stark effect was mainly observed in the presence of an external electric field. Changes in parameters such as the dipole moment and polarizability between the ground and the Franck–Condon excited states of the PTCDI monomer were determined. The fluorescence spectrum shows a contribution from a broad fluorescence band at wavelengths longer than the monomer fluorescence band. This broad fluorescence is ascribed to the excimer-like fluorescence of PTCDI. The effects of the electric field on the fluorescence spectrum, known as the Stark fluorescence or electrofluorescence spectrum, were measured. Fluorescence quenching is observed in the presence of an external electric field. The change in the polarizability of the monomer fluorescence band is in good agreement with that of the electroabsorption spectrum. A larger change in the polarizability was observed for the excimer-like fluorescence band than that for the monomer band. This result is consistent with exciton delocalization between PTCDI molecules in the excimer-like state.

Perylenetetracarboxylic Diimide Composite Electrodes as Organic Cathode Materials for Rechargeable Sodium-Ion Batteries: A Joint Experimental and Theoretical Study.

The organic semiconductor 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), a widely used industrial pigment, has been identified as a diffusion-less Na-ion storage material, allowing for exceptionally fast charging/discharging rates. The elimination of diffusion effects in electrochemical measurements enables the assessment of interaction energies from simple cyclic voltammetry experiments through the theoretical work of Laviron and Tokuda. In this work, the two N-substituted perylenes, N,N'-dimethyl-3,4,9,10-perylenetetracarboxylic diimide (Me2PTCDI) and N,N'-diphenyl-3,4,9,10-perylenetetracarboxylic diimide (Ph2PTCDI), as well as the parent molecule 3,4,9,10-perylenetetracarboxylic diimide (H2PTCDI) are investigated as thin-film composite electrodes on carbon fibers for sodium-ion batteries. The composite electrodes are analyzed with Raman spectroscopy. Interaction parameters are extracted from cyclic voltammetry measurements. The stability and rate capability of the three PTCDI derivatives are examined through galvanostatic measurements in sodium-ion half-cell batteries and the influence of the interactions on those parameters is evaluated. In addition, self-consistent charge density function tight binding calculations of the different PTCDI systems interacting with graphite have been carried out. The results show that the binding motif displays notable deviations from an ideal ABA stacking, especially for the neutral state. In addition, data obtained for the electron-transfer integrals show that the difference in performance between different PTCDI thin-film batteries cannot be solely explained by the electron-transfer properties and other factors such as H-bonding have to be considered.

Low-Cost and Sustainable Aqueous Lithium-Ion Batteries by All-Organic PTCDI Anodes

Electrolyte engineering has been key to the advancement of aqueous lithium-ion batteries (ALIBs), for example, the introduction of water-in-salt electrolytes (WiSEs) has enabled ALIBs to cycle well and to operate at potentials far beyond the electrochemical stability window of water. WiSEs are, however, intrinsically based on high concentrations of salt(s) which furthermore often are expensive and fluorinated, and therefore defeats the aim of ALIBs being low-cost and sustainable. Strategies to circumvent this issue have been to add co-solvents and/or diluents to decrease the overall electrolyte concentration or customize the anion and salt concentration to each battery chemistry. The clean and green ethos of ALIBs can be enhanced by using organic active materials (AMs), but these are unfortunately often water soluble and therefore requires an electrolyte designed to mitigate dissolution/electrode de-attachment.Herein, we for the first time implement perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) as the anode AM for ALIBs. We demonstrate that by appropriate aqueous electrolyte selection we can truly mitigate electrode de-attachment, leading to excellent properties in terms of capacity, rate capability, cycling stability, and Coulombic efficiency. All things considered, this endeavour intends to further reduce the kWh/€ and thereby reinforcing the feasibility of more cost-effective large-scale battery energy storage solutions Fig 1. Long term galvanostatic cycling of an all-organic PTCDI electrode in a PTCDI/low conc. aqueous el./LFP cell set-up. Inset shows the chemical structure of PTCDI and the corresponding charge/discharge voltage curves. Figure 1

Novel highly sensitive fluorescence probe based on Perylene diimide for formaldehyde in real food samples

A formaldehyde (FA) fluorescence probePDSNwith two hydrazone groups as the recognition site based on the Perylene tetracarboxylic diimide (PDI) skeleton was synthesized, applied in the recognition of FA in food. The probe PDSN presented an obvious color change from purple to bright yellow after the addition of FA. The fluorescent mechanism of PDSN was also confirmed by 1H NMR. Moreover,PDSNexhibited excellent sensitivity, high selectivity, wide pH values, and a low detection limit of 11.2 nM. Satisfactory results were obtained in the water and real food samples in great accordance with an impressed recovery rate and RSD.

Spontaneous electrochemical stabilization of nanostructured organic electrodes by field-induced charge-transfer

Organic electrodes are promising candidates for the next-generation energy storage system of rechargeable lithium-ion batteries (LIBs) due to their natural abundance and lightweight. However, they have weaknesses: low electrochemical capacity, low capacity retention, and elution of active electrode materials. In this study, the field-induced charge-transfer route and nanostructuring are developed to resolve the poor electrochemical performance. When the 5,10-Dihydro-5,10-dimethylphenazine (DMPZ) with a nanoporous structure is homogeneously mixed with organic and metal nanoparticles (perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), perylenetetracarboxylic diimide (PTCDI), Flavanthrone, and Aluminum), the organic nanocomposite cathodes exhibit a remarkable enhancement in electrochemical performance: unprecedented cycling stability with capacity retention over 90% up to 600 redox cycles, a high specific capacity of 215 mA·h·g−1 at the current density of 150 mA·g−1, and an excellent rate-capability for the DMPZ and PTCDA nanocomposite cathode. The excellent specific capacity and retention of the redox reaction are due to the fast charge transport through the nanoporous network of the nanocomposites with a high specific surface area. The charge-transfer between the vicinal organic materials with different ionization energies is induced by the charging potential of the redox reaction, which suppresses the elution during the oxidation process and leads to the remarkable cyclability. The all-organic pouch-type full-cell, composed of a PTCDI anode and the nanocomposite cathode, is realized with excellent cyclability of 76% capacity retention at the 200th cycle. This work provides a promising way of developing stable organic electrodes for electrocatalytic applications as well as LIBs.

Dendrite-free potassium metal anode induced by in-situ phase transitions of MoS2

Potassium ion batteries (PIBs) are identified as an imperative alternative for next-generation energy storage devices due to its abundant reserves. Even potassium (K) metal is a promising anode for its high theoretical capacity and intrinsic low potential, however, it still suffers from uncontrollable dendrite growth. Herein, a dendrite-free K anode is obtained by plating K metal on MoS2-modified carbon cloth (MoS2/CC@K). Specifically, MoS2 undergoes a series of phase transitions from initial MoS2 to KxMoS2 and final K2S4 with gradual insertion of K, then K metal is uniformly deposited on K2S4 with further discharging. This phase transition significantly reduces the K nucleation energy barrier. The strong interaction between K and K2S4 interface induces K in uniformly depositing to suppress the formation of K dendrites. Owing to these merits, the symmetric MoS2/CC@K cells exhibit low voltage hysteresis and superior cycling stability. When paired with perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) cathode, the full cells display superior rate capability and long lifespan (10,000 cycles). Additionally, this strategy is also performed on Li and Na metal anodes, the MoS2/CC substrate still expresses superior electrochemical performance. This work provides a new view to induce the uniformly deposition of K, Li and Na metals.

A Solar Responsive Battery Based on Charge Separation and Redox Coupled Covalent Organic Framework

AbstractSolar‐responsive battery holds great promise in solar‐to‐electrochemical energy storage, but is impeded by the lack of efficient photoelectrochemical‐cathodes. Herein, a crystalline mesoporous (≈4.0 nm) covalent organic framework (TA‐PT COF) with repeating units consisting of covalently linked triphenylamine (TPA) and perylenetetracarboxylic diimide (PTCDI) is presented. The repeating unit functions as both a donor–acceptor pair and a dual‐redox site to realize a molecule‐level coupling of intramolecular charge separation (τCS = 136.2 ps, τCR = 949 ps) and reversible redox chemistry (C=O/CO−, TPA/TPA+). Equipped with this photoelectrochemical cathode, a reversible aqueous solar‐responsive battery delivered a reliable voltage‐response of 376 mV, an extra round‐trip efficiency of 35% and a good light durability (500 cycles). A photo‐coupled electron/mass transfer mechanism of photoelectrons for Zn2+ storage and holes for OTf− storage is further revealed, shedding light on a new photoelectrochemical cathode design based on charge separation and redox‐coupled COF for efficient solar‐responsive batteries.

Effective fluorescent turn-on detection of ionizing radiations through controllable intramolecular photoinduced electron transfer

In order to explore the detection of gamma radiation via intramolecular photoinduced electron transfer (PET) and the interaction between molecular structures and fluorescence enhancement, we conducted an in-depth study of the perylene tetracarboxylic diimide (PDI) series of fluorescent probes capable of detecting HCl in the non-polar CHCl3 solutions. To simulate the interaction between ionizing radiation and fluorescent molecules, we used HCl titration method to predict the ability of PDI-n to detect gamma rays. The results show that the combination of PDI-n and HCl can enhance the fluorescence through retro-PET process. In addition, the fluorescence enhancement multiple gradually decreased with the enlargement of alkylamine side chains. In the direct irradiation experiment of ionizing radiation, PDI-n can also show a good fluoresence enhancement to gamma rays. Similar to the above HCl titration tests, the fluorescence increament stronthly depends on the alkylamine side chains lengths. The maximum fluorescence increament of PDI-1 is 22.24, and the fluorescence enhancement multiple of PDI-1–PDI-4 decreases when increasing the alkyl chain length. Besides, combining density functional theory (DFT), time-dependent density functional theory (TDDFT) calculations and electrochemical tests, the relative positions of each energy level obtained from the experiment indicate that the PDI-n molecule is beneficial to the occurrence of the intramolecular PET effect. Using femtosecond transient absorption spectroscopy (fs-TAS) and transient fluorescence spectroscopy (TFS) tests, the lifetime of charge separation was obtained, and the efficiency of the PET process was characterized by the rate constant. We found that fluorescent molecules with shorter side chains can realize PET more efficiently. Therefore, this work exploits the intramolecular PET mechanism for efficiently detecting gamma rays using a series of fluorescent probes, and reveals the law of the influence of molecular chain length on the PET effect. Which provides theoretical support for the development of new materials for effective and sensitive detection of ionizing radiation.

Urea-Based Deep Eutectic Solvent with Magnesium/Lithium Dual Ions as an Aqueous Electrolyte for High-Performance Battery-Supercapacitor Hybrid Devices

A new deep eutectic solvent (DES) made from urea, magnesium chloride, lithium perchlorate and water has been developed as the electrolyte for battery-supercapacitor hybrid devices. The physicochemical characteristics of DES electrolytes and potential interactions between electrolyte components are well analyzed through electrochemical and spectroscopic techniques. It has been discovered that the properties of DES electrolytes are highly dependent on the component ratio, which allows us to engineer the electrolyte to meet the requirement of the battery application. Perylene tetracarboxylic di-imide and reduced graphene oxide ha ve been combined to produce a composite (PTCDI/rGO) that has been tested as the anode in DES electrolyte. This composite shows that the capacitive contribution is greater than 90% in a low scan rate, resulting in the high rate capability. The PTCDI/rGO electrode exhibits no sign of capacity degradation and its coulombic efficiency is close to 99% after 200 cycles, which suggests excellent reversibility and stability. On the other hand, the electrochemical performance of lithium manganese oxide as the cathode material is studied in DES electrolyte, which exhibits the maximum capacity of 76.5 mAh/g at 0.03 A/g current density. After being successfully examined in terms of electrode kinetics, capacity performance, and rate capability, the anode and cathode materials are combined to construct a two-electrode system with DES electrolyte. At a current density of 0.03 A/g, this system offers 43.5 mAh/g specific capacity and displays 55.5% retention of the maximum capacity at 1 A/g. Furthermore, an energy density of 53 Wh/kg is delivered at a power density of 35 W/kg.

S-scheme enhanced photocatalysis on graphitic carbon nitride functionalized with perylene tetracarboxylic diimide

It is a challenge to realize the catalytic conversion of ammonia by photocatalysis under mild conditions, because it is limited by the high photoinduced carrier recombination rate and low photo-absorption efficiency. Herein, we perform the condensation reaction of 3,4,9,10-perylenetetracarboxylic diimide (PTCDA) with graphitic carbon nitride (g-C3N4) nanosheets to obtain a novel organic semiconductor perylene tetracarboxylic diimide (PTCDI) modified g-C3N4 S-scheme heterostructure (named PTCDI@g-C3N4) via thermal-etching and bath process. The obtained PTCDI@g-C3N4 composite shows an obvious improvement in photocatalytic nitrogen reduction rate of 7308.9 μmol L−1 g−1h−1 with methanol under the Xe lamp irradiation, higher than g-C3N4 nanosheets (1215.3 μmol L−1 g−1 h−1). The excellent photocatalytic performance of PTCDI@g-C3N4 heterostructure is ascribed to two advantages: (1) The S-scheme heterojunction between organic semiconductor PTCDI and g-C3N4 nanosheets is profit to suppress carrier recombination and enhance electron utilization efficiency; (2) The utilization rate of g-C3N4 nanosheets to light was promoted due to the existence of PTCDI with broad visible light absorption. This work may help to provide a possibility to realize efficient photocatalytic nitrogen fixation by preparing organic-nonmetallic heterostructure through facile methods.

Reversible piezochromic sensors based on the complex of two-dimensional layered materials and polymer

The potential use of prominent piezochromic materials in optical recording and mechanical sensors has sparked widespread interest. However, the luminescence quenching effect caused by the aggregation of photo-functional molecules and their disordered stacking have limited the development in piezochromic field. Here, perylene-3,4,9,10-tetracarboxylic diimide (PDI) was selected as the chromophore, layered double hydroxide (LDH) as the inorganic matrix, and polyvinyl alcohol (PVA) as the film-forming material to jointly construct the (PDI-LDH@PVA) film. The film shows a fluorescence sensitive response to the external pressure due to the changed interaction force between the three components. The confinement effect of LDH enables PDI molecules to form a highly ordered structure in a stretchable free space, giving pressure sensor a larger response range and good reversibility. This work provides design rules for the construction of pressure-sensitive systems, which will guide the development of advanced photo-functional materials.

Hybrid perylene-cored poly(amidoamine) dendrimer with coumarin and calcozine red 6G end groups: From photophysical properties to cell imaging

In this article, we looked at how to make fluorescence hybrid dendrimers using perylenediimide (PTCDI) cores and calcozine red 6 G and coumarin end groups. Perylenetetracarboxylic dianhydride (PTCDA) is used as core, and 4th generation poly(amidoamine) dendrimer (PAMAM) is synthesized to produce PG4.0. Then, PG4.0 is reacted with calcozine red 6 G and 7-methacryloyloxy-4-methylcoumarin (MCMC). Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) are used to characterize the structure of synthesized fluorescent hybrid dendrimers. Optical properties are demonstrated using fluorescence microscopy, a fluorescence spectrophotometer, and UV–vis–NIR reflectance spectra. Hybrid dendrimers were transparent in the NIR range, according to UV-Vis-NIR reflectance spectra. Moreover, quantum yield (Φs) of hybrid dendrimers was calculated in dimethylformamide (DMF), ethanol, and distilled water (H2O). PG4R32 and PG4M16R16 showed the maximum quantum yield in ethanol due to great interaction of structure with ethanol and the arrangement of ring-opened amide shape of calcozine red 6 G gather in compound. At long last, SH-SY5Y cells were utilized to measure cell uptake and fluorescence imaging exhibitions of PG4.0 (perylene-3,4,9,10-tetracarboxylic diimide (PTCDI)-based generation 4 amino terminated poly(amidoamine)dendrimers), PG4M32 (perylene-3,4,9,10-tetracarboxylic diimide (PTCDI)-based generation 4 amino terminated poly(amidoamine)dendrimers in which 32 amine groups of PAMAM are conjugated with coumarin derivatives), PG4R32 (perylene-3,4,9,10-tetracarboxylic diimide (PTCDI)-based generation 4 amino terminated poly(amidoamine)dendrimers in which 32 amine groups of PAMAM are conjugated with rhodamine derivatives), and PG4M16R16 (perylene-3,4,9,10-tetracarboxylic diimide (PTCDI)-based generation 4 amino terminated poly(amidoamine)dendrimers in which 16 amine groups of PAMAM are conjugated with rhodamine and coumarin derivatives) pigments, and as a result, pigments had a great capacity for live-cell fluorescence imaging.

Synthesis, optical properties, and cell imaging performance of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI)-based poly(amidoamine) (PAMAM) dendrimers

Poly(amidoamine) (PAMAM) dendrimers up to 4th generation are designed and synthesized via a divergent method based on perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) as a luminescent core. Success of syntheses is proved by different analyses such as Fourier-transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Due to the photo-induced electron transfer (PET), these systems are configured as a “fluorophore-spacer-receptor”. Results showed that PTCDI-cored dendrimers had semi-crystalline structure with appropriate thermal stability. UV–Vis-NIR reflectance spectra showed that PTCDI-cored PAMAM dendrimers were generation-dependent NIR adsorbent or transparent in the NIR region. MTT assay against SH-SY5Y cells showed that PG4.0 was rather cytocompatible and solubility, compatibility, and fluorescent properties of core were improved by generation progression of dendrimers. Finally, SH-SY5Y cells were used to measure cell uptake and fluorescence imaging performances of PG4.0 pigment which showed a good ability to live-cell fluorescence imaging.

A 1.9-V all-organic battery-supercapacitor hybrid device with high rate capability and wide temperature tolerance in a metal-free water-in-salt electrolyte

Developing battery-supercapacitor hybrid devices (BSHs) is viewed as an efficient route to shorten the gap between supercapacitors and batteries. In this study, a composite hydrogel consisting of perylene tetracarboxylic diimide (PTCDI) and reduced graphene oxide (rGO) is tested as the anode for BSHs in the electrolyte of ammonium acetate (NH4Ac) with a record concentration of 32 molality (m). This water-in-salt electrolyte exhibits a wide electrochemical stability window of 2.13 V and high conductivity of 23.3 mS cm−1 even at −12 °C. Molecular dynamics calculations and spectroscopic measurements reveal that a favorable water-acetate interaction occurs in a high concentration NH4Ac electrolyte. On the other hand, the study of electrode kinetics in 32 m NH4Ac demonstrates a high capacitive contribution to charge storage in PTCDI-rGO although an electrode redox reaction involves reversible enolization of carbonyl groups in PTCDI. This result suggests fast NH4+-ion intercalation kinetics in charge–discharge processes. Furthermore, the electrode performance is improved by optimizing the loading amount of rGO in composites. The best-performing composite electrode delivers the maximum capacity of 165 mAh g−1 at 0.5 A g−1 and sustains a great capacity retention of 66% at 8 A g−1. Finally, an all-organic BSH device is tested in a broad temperature window from −20 to 50 °C and is well operated at 1.9 V regardless of operating temperatures. Due to the synergetic effect of splendid electrolyte properties and high anode capacities, BSH devices possess the maximum energy density of 12.9 Wh kg−1 at the power density of 827 W kg−1 and retain 74 % of the initial capacity after 3000 cycles at 1 A g−1. Our study paves a novel route towards designing inexpensive and environmentally friendly BSH devices with high performances.

Tailor-made organic polymers towards high voltage aqueous ammonium/potassium-ion asymmetric supercapacitors

Engineering the polymers with electrochemical functionality is a topic of contemporary research towards developing lightweight and low-cost energy storage devices. In this study, a pair of organic polymers is successfully synthesized by coupling the redox-active moieties such as perylenetetracarboxylic diimide together through monosulfide and disulfide groups. The introduction of two different sulfide linkages in the polymeric chain yields two distinct morphologies due to the different structures of sulfide linkage groups. These polymers are tested as the electrode materials for supercapacitors in two different water-in-salt electrolytes. The interactions of K+/NH4+ ions with polymer electrodes are separately studied in 27 m potassium acetate (KAc) and 27 m ammonium acetate electrolytes. The polymer with monosulfide moieties shows better specific capacitance, rate capability, and cyclic stability in 27 m KAc compared to the one with disulfide moieties. In order to demonstrate the practical application, the asymmetric supercapacitors are fabricated by using the polymer and activated carbon as the negative and positive electrodes, respectively. The device with 27 m KAc delivers an energy density of 29.9 Wh kg−1 at the power density of 850 W kg−1 and exhibits 79% of the initial capacitance after 10,000 charge-discharge cycles at the current density of 2 A g−1.

Porous p–n junction-induced memory characteristics in low-voltage organic memory transistors

Low-voltage organic memory transistors (LOMTs) as data storage units are crucial for the advancements of future flexible electronics. However, charge storage mechanism remains a great challenge. In this work, we used poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno(3,2-b)thiophene) (PBTTT-C14) as the active layer and incorporated poly(methyl methacrylate) (PMMA) with the PBTTT-C14 through a simple blending process to fabricate LOMTs with porous structure. The function of the porous structure was to improve the carrier traps, which can effectively capture the holes at the charge trapping regions during the programming process. A maximum threshold voltage shift of 1.01 V was achieved when the weight ratio of PBTTT-C14 and PMMA is 7:3, and the LOMTs were operated under the programming process of −4 V/1 s. Impedance-admittance analyses were used to investigate the interfacial trap density of charge trapping regions, which is a supporter of the programming capability of LOMTs. An ultrathin dioctyl perylene tetracarboxylic diimide film was deposited on the active layer with porous structure in LOMTs. This film can increase the carriers’ erasing capability. A wide memory window of 1.64 V was obtained in LOMTs when the devices are operated under the erasing process of bias pulse of 3 V/1 s with the assistance of 2.5 mW cm−2 light irradiation. This study facilitates the development of high-performance LOMT device in fresh-type memory.

Photoinduced electron transfer for improved FET performance based on the hybrid film of an amphiphilic perylene diimide and CdS

A new organic/inorganic PDI/CdS hybrid film is fabricated by using a solution-based Langmuir–Shäfer method, inwhich uniformed chrysanthemum-like CdS nanocrystals with an average diameter of ca.120 nm grow in-situ on the Langmuir monolayer of an amphiphilic perylene tetracarboxylic diimide derivative bearing 3,4,5-triethyleneglycolmonomethyletherphenyl substituents on the imide N atoms and four phenoxy-type substituents in the bay positions of the perylene core (referred to as PDI). Organized film microstructures and slipped co-facialmolecular stacking mode with the “edge-on” conformation are revealed for the PDI in both pure film and hybrid film, with a slightly increased orientation angle with respect to the substrate from 65.4° to 66.8° after incorporation of CdS nanoparticles into the PDI film matrix. Impressively, the electron-transfer from the organic layer to CdS nanocrystals is inferred by both changing the lifetime of photoluminescence emission of PDI in the hybrid film and band structure analysis for PDI and CdS. In particular, upon irradiation of 365 nm UV light, a significantly enhanced electron transport has been obtained in PDI/CdS-based thin film transistors with the carrier mobility up to 1.64 × 10-3 cm2/V•s for electrons, which is two orders of magnitude higher than that (1.91 × 10-5 cm2/V•s) without the irradiation.

Synthesis and properties of fluorescent coumarin/perylene-3,4,9,10-tetracarboxylic diimide hybrid as cold dye

Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) was modified by ethylenediamine to obtain perylene-3,4,9,10-tetracarboxylic diimide (PTCDI). PTCDI as an initial core was used to bond coumarin derivatives. Successful conjugating of coumarin derivatives onto PTCDI was confirmed by Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), and field emission scanning electron microscope (FE-SEM). XRD peaks of various samples showed that the crystalline structure of PTCDA retained during the modification processes. The morphology of the nanoparticles by FE-SEM showed that the dyes were fibrillar. Fluorescence microscopy was used to evaluate the fluorescence properties of the dyes. In order to determine the amount of absorption and reflection in the near-infrared region, NIR test was used in both white and black fields. High absorption on a white background and high reflection on a black background indicated the transparency of the dye in the near-infrared region. The synthesized dye was identified and reported as a cold dye.

Perylenetetracarboxylic diimide covalently bonded with mesoporous g-C3N4 to construct direct Z-scheme heterojunctions for efficient photocatalytic oxidative coupling of amines

Photocatalytic oxidative coupling of amines is a promising method for imine synthesis. In this paper, a robust covalently-bonded direct Z-scheme heterostructure (PDI/mpgCN) for photocatalytic oxidative coupling of amine was reported for the first time. Perylenetetracarboxylic diimide (PDI) molecules were covalently connected to the surface of mesoporous carbon nitride (mpgCN) via an in-situ condensation strategy. Compared with the poor conversion efficiency upon pristine g-C3N4, PDI/mpgCN heterostructure exhibits a remarkable enhancement on amine oxidation rate (AOR), with the optimal AOR reaches to as high as 20.63 mmol g−1 h−1 upon 20 % PDI/mpgCN. As far as we know, it is the highest AOR achieved so far for amine photooxidation coupling with heterojunction materials. Transient absorption studies proved the formation of Z-scheme junction, and efficient interfacial charge transfer. Our study not only makes an insight into the heterojunction design with chemical bond precision, but highlights the great prospects of Z-scheme photocatalyst in photo-chemical synthesis.

Light-Induced Charge Accumulation in PTCDI/Pentacene/Ag(111) Heterojunctions

The incorporation of singlet fission (SF) chromophores in solar cells is expected to bring significant increases in the power conversion efficiency thanks to multiexciton generation. However, efficient charge generation in the device is determined by the energy level alignment (ELA) between the active materials, which should favor exciton transport and separation under illumination. By combining ultraviolet photoemission spectroscopy and optical differential reflectance measurements, we determine the ELA in a prototypical SF heterojunction between pentacene (Pc) and perylene-tetracarboxylic-diimide (PTCDI) grown on Ag(111). Time-resolved X-ray photoelectron spectroscopy on such a system reveals light-induced modifications of the ELA; by measuring the transient shift of the core level photoemission lines we observe an accumulation of long-lived holes in the PTCDI within the first hundred picoseconds after the optical pump.