Ionization Potential Values Research Articles

An investigation into the structural, electronic, and non-linear optical properties in CN (N = 20, 24, 26, 28, 30, 32, 34, 36, and 38) fullerene cages.

The present study attempts to investigate the structural, electronic, and non-linear optical properties of CN (N = 20, 24, 26, 28, 30, 32, 34, 36, and 38) fullerene cages based on Density Functional Theory (DFT). In the DFT calculations, the B3LYP/6-311G(d,p) and CAM-B3LYP/6-311 + + G(d,p) level of theories were used. The isomers of each fullerene have been received from the Fullerene Structure Library. These isomers have optimized using the B3LYP/6-311G(d,p). The results included optimization of the neutral and ionic state structures according to their multiplicity. Geometries, optimization energies, relative energies, frequencies, HOMO, LUMO, and HOMO-LUMO gap of these stable fullerene cages have been predicted by B3LYP/6-311G(d,p). Afterwards, the most stable structures have been re-optimized using the CAM-B3LYP /6-311 + + G(d,p). Finally, non-linear optical properties, Fukui functions, density of state, electron affinity, and ionization potential values of the most stable fullerene cages have been found out by the DFT/ CAM-B3LYP /6-311 + + G(d,p) level of theory. All calculation results have been compared with both C60 fullerene and the relevant literature on corresponding fullerenes.

Designing limiting-efficiency BaSi[formula omitted] solar cells by device simulation and computational material screening

A double heterojunction solar cell consisting of a solar absorber and electron/hole transport layers (ETL/HTL) is ideally efficient and can contribute to the exploitation of solar energy. BaSi2 is an attractive solar absorber material possessing a band gap of 1.3 eV and high absorption coefficients. However, finding proper ETL/HTL materials remains challenging. Here, limiting efficiency calculation, device simulation, and computational material screening are combined to design BaSi2 solar cells of near-limiting efficiency (> 28%). The limiting efficiency is calculated considering radiative and trap-assisted Auger recombinations, which shows that the Lambertian limit efficiency (32%) exceeds that of Si cells. Device simulations of double heterojunction BaSi2 cells were performed with different values of band gap, ionization potential, and electron affinity, which yields criteria for band-edge energy levels of the ETL and HTL. Candidate materials for the ETL and HTL are identified from the Materials Project database by three-step screening. The first step screens the materials for band gap, interface reactivity, lattice matching, etc. The second step is a literature survey to exclude air-sensitive or unstable materials under ambient conditions. In the third step, band-edge levels are calculated using density functional theory, and eight ETL and seven HTL candidate materials are identified. This device design method is applicable to any solar absorber material and promotes accelerated solar cell development.

Facile construction of Z-scheme AgBr/BiO(HCOO)0.75I0.25 photocatalyst for visible-light-driven BPA degradation: Catalytic kinetics, selectivity and mechanism

Herein, a novel AgBr/BiO(HCOO)0.75I0.25 Z-scheme photocatalyst was constructed through a facile hydrothermal and post-precipitation method for visible-light (VL) driven wastewater remediation. The 10 wt% AgBr/BiO(HCOO)0.75I0.25 composite (10%ABB) could completely decompose bisphenol A (BPA) within 25 min, and multiple coexisting inorganic anions and natural organic matters only slightly affected the BPA removal efficiency. The wonderful photocatalytic performance could attribute to the construction of Z-scheme heterojunction, which modulated the energy band, accelerated the electron transfer and also raised the redox ability of the system. Since the superoxide radicals (O2−) and non-radical pathway (1O2 and h+) were proved to be the dominating reactive species, 10%ABB/VL system exhibited a highly selective oxidation on aromatics with electron donating groups, whereas a relatively low value for organics with electron with drawing groups. By investigating the ionization potential (IP) of five representative organics, a negative correlation between IP value and reaction kinetics was reported. Moreover, the possible photocatalytic mechanism and elimination pathway were proposed via a series of photoelectrochemical analysis and LC-MS/MS. This work provides a strategy for engineering novel Bi-based photocatalyst and establishing selective oxidation system for organic contamination removal.

High-accuracy Rb2+ interaction potentials based on coupled-cluster calculations

This work discusses a protocol for constructing highly accurate potential energy curves (PECs) for the lowest two states of Rb$_{2}^+$, i.e. $X\,{}^2{\Sigma}{_g^+}$ and $(1) {}^2\Sigma{_u^+}$, using an additivity scheme based on coupled-cluster theory. The approach exploits the findings of our previous work [J. Schnabel, L. Cheng and A. K\"ohn, J. Chem. Phys. 155, 124101 (2021)] to avoid the unphysical repulsive long-range barrier occurring for symmetric molecular ions when perturbative estimates of higher-order cluster operators are employed. Furthermore, care was taken to reproduce the physically correct exchange splitting of the $X {}^2{\Sigma}{_g^+}$ and $(1) {}^2{\Sigma}{_u^+}$ PECs. The accuracy of our computational approach is benchmarked for ionization energies of Rb and for spectroscopic constants as well as vibrational levels of the $a {}^3{\Sigma}{_u^+}$ triplet state of Rb\textsubscript{2}. We study high-level correlation contributions, high-level relativistic effects and inner-shell correlation contributions and find very good agreement with experimental reference values for the atomic ionization potential and the binding energy of Rb$_{2}$ in the $a\,{}^3{\Sigma}{_u^+}$ triplet state. Our final best estimate for the binding energy of the Rb$_{2}^+$ $X {}^2{\Sigma}{_g^+}$ state including zero-point vibrational contributions is $D_0 = 6179\,\mathrm{cm}^{-1}$ with an estimated error bound of $\mathcal{O}(\pm 30\,\mathrm{cm}^{-1})$. This value is smaller than the experimentally inferred lower bond of $D_0\ge 6307.5\,\mathrm{cm}^{-1}$ [Bellos et al., Phys. Rev. A 87, 012508 (2013)] and will require further investigation. For the $(1) {}^2{\Sigma}{_u^+}$ state a shallow potential with $D_0 = 78.4\,\mathrm{cm}^{-1}$ and an error bound of $\pm 9\,\mathrm{cm}^{-1}$ is computed.

A systematic computational study of acridine derivatives through conceptual density functional theory.

A detailed computational analysis of acridine derivatives viz. acridone, 9-amino acridine hydrochloride hydrate, proflavin, acridine orange and acridine yellow is done in terms of conceptual density functional theory (CDFT). CDFT-based global descriptors-ionization potential, electron affinity, HOMO-LUMO gap, hardness, softness, electronegativity and electrophilicity index of acridine derivatives for ground state as well as excited state are estimated with the help of different hybrid functionals B3LYP/6-31G (d, p), B3LYP/6-311G (d, p), B3LYP/DGDZVP and B3LYP/LANL2DZ. Acridine derivatives show higher values of ionization potential and electron affinity in excited state as compared to ground state, indicating that these compounds are willing to accept electrons in excited state rather than donating electron. Acridone shows the maximum HOMO-LUMO energy gap in ground and excited state which implies that one-way electron transfer is most feasible with this compound. Our computed results emphasize the pronounced electron acceptor behaviour of the acridine derivatives in the excited state which has already been experimentally verified. It is observed that the trend in the computed values of the descriptors is not much improved on refinement of the basis set.

DFT study of transition metals doped calix-4-pyrrole with excellent electronic and non-linear optical properties

Herein a detailed comparative study on the transition metal doped calix-4-pyrrole was carried out to determine the optical, electronic, and non-linear optical (NLO) properties, as well as to synthesize some thermodynamically stable complexes. All the computational work was accomplished using density functional theory (DFT). The optical and chemical properties of Sc[CPM1]Sc, Ti[CPM1]Sc, Sc[CPM1]Ti, and Ti[CPM1]Ti were seen to be superior to the un-doped cage. Doping of transition metals inside and outside the cage increased the diffused excess electrons, as a result lowering the energy gap (from 4.01 to 2.15 eV). Due to these excess electrons and lower excitation energy, noteworthy increasement took place in the polarizability and hyperpolarizability of all doped structures. The minimum energy gap (2.15 eV) and largest first hyperpolarizability (16360 a.u) was observed for Sc[CPM1]Sc. Non-covalent interaction (NCI) analysis illustrated that the intermolecular forces are the major cause of interaction between the cage and dopants. It was also indicated from the density of state (DOS) and frontier molecular orbital (FMO) diagrams that the transition metals significantly raised the distribution of charge density in the structures under study, especially in Sc[CPM1]Sc, while the capability to transfer charges was revealed from transition density matrix (TDM) graphs. Natural bond orbital (NBO) charge analysis revealed that transfer of charges occurred from the dopants towards the surface. Calculated values of interaction energy, binding energy, and vertical ionization potential confirmed the thermo-dynamical stability of the molecules. Time-dependent DFT measures were conducted to evaluate all the necessary transitions and absorption analysis. Consequently, all the calculated parameters praised the capability of our designed molecules in the field of electronics and non-linear optics.

D-A-D Compounds Combining Dithienopyrrole Donors and Acceptors of Increasing Electron-Withdrawing Capability: Synthesis, Spectroscopy, Electropolymerization, and Electrochromism.

Five D-π-A-π-D compounds consisting of the same donor unit (dithieno[3,2-b:2′,3′-d]pyrrole, DTP), the same π-linker (2,5-thienylene), and different acceptors of increasing electron-withdrawing ability (1,3,4-thiadiazole (TD), benzo[c][1,2,5]thiadiazole (BTD), 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP), 1,2,4,5-tetrazine (TZ), and benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (NDI)) were synthesized. DTP-TD, DTP-BTD, and DTP-DPP turned out to be interesting luminophores emitting either yellow (DTP-TD) or near-infrared (DTP-BTD and DTP-DPP) radiation in dichloromethane solutions. The emission bands were increasingly bathochromically shifted with increasing solvent polarity. Electrochemically determined electron affinities (|EA|s) were found to be strongly dependent on the nature of the acceptor changing from 2.86 to 3.84 eV for DTP-TD and DTP-NDI, respectively, while the ionization potential (IP) values varied only weakly. Experimental findings were strongly supported by theoretical calculations, which correctly predicted the observed solvent dependence of the emission spectra. Similarly, the calculated IP and EA values were in excellent agreement with the experiment. DTP-TD, DTP-BTD, DTP-TZ, and DTP-NDI could be electropolymerized to yield polymers of very narrow electrochemical band gap and characterized by redox states differing in color coordinates and lightness. Poly(DTP-NDI) and poly(DTP-TD) showed promising electrochromic behavior, not only providing a rich color palette in the visible but also exhibiting near-infrared (NIR) electrochromism.

The Evolution of Geometric Structures, Electronic Properties, and Chemical Bonding of Small Phosphorus-Boron Clusters

We report a comprehensive theoretical investigation on phosphorus–boron mixed neutral, anionic, and cationic clusters P2Bn/P2Bn−/P2Bn+ (n = 3–7) with two phosphorus atoms and three to seven boron atoms. We reveal the common character of all the structures (i.e., the phosphorus atoms choose to occupy the peripheral position), whereas the boron atoms tend to be in the central and inside position of the ground state phosphorus—boron mixed clusters at each stoichiometry. Any three atoms preferentially form a stable triangle and grow with zigzag shape in a planar network. Interestingly, a series of planar motifs (including tetra-, penta-, and hexa-coordination) have been discovered in the phosphorus–boron clusters. The large binding energies (3.6 to 4.6 eV/atom) and quite large HOMO–LUMO gaps (5 to 10 eV) indicate the high stability of the clusters. The energy differences Δ1E, Δ2E, and energy gaps display oscillating behavior with increasing numbers of boron atoms. The electron affinity (EA) and ionization potential (IP) generally have small variations, with the EA values ranging from 2 to 3 eV, and the IP values ranging from 7 to 9 eV. Chemical bond analysis shows that the existence of multi-center delocalized bonds stabilize the clusters.

New approach of mechanochromic, thermally activated delayed fluorescence’ dyes consisting of “thioxanthenone derivative as an acceptor unit and two carbazole derivatives as the donor units” used as emitting layer in organic light-emitting diodes

Two dyes containing of thioxanthenone derivative as an acceptor unit, were designed and synthesized for thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs). The photoluminescence (PL) spectra of hammered dyes were shifted and the dyes were mechanochromic. Ionization potential (IP) values of spin-coated dyes on the fluorine-tin oxide film ranged from −5.42 to −5.49 eV and the hole mobility values reached to 2.64 × 10−4 and 3.56 × 10−4 cm2 V−1s−1. Considering the higher values of the photoluminescence quantum yields (PLQYs) of spin-coated dyes on the solid films (16, 21%) that dispersed the dyes in a solution such as toluene (7, 3%), the aggregation induced emission enhancement (AIEE) phenomena were observed. In addition, the doped devices were fabricated based on 50 wt% poly (9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB) as a host material through the solution process and physically evaporation deposition (PVD). In this study, the effect of utilizing 4, 4′, 4″-Tris [(3-methylphenyl) phenylamino]triphenylamine (m-MTDATA) as a hole transport layer was impressive and the exciplex forming was confirmed. Finally, the electroluminescence with CIE(x,y) of (0.2076,0.3634) was resulted for the device consisted of low turn on voltage of 4.43 V, maximum brightness of 21362.55 cd m−2, maximum current and power efficiency of 27.03 cd A−1 and 19.65 lm.W−1 and maximum external quantum efficiency of 9.71%.

Synthesis and investigation of the theoretical and experimental optical properties of some novel azo pyrazole sulfonamide hybrids

In this study, we have designed and investigated four new low-emitting fluorescent dyes consisting of sulfonamide derivatives with substitution groups in the LUMO moiety. In these dyes, sulfonamide linked with pyrazole group played an important role in complementing the acceptor moieties. The optical properties of dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay time analysis in the non-doped solid film. The strong effect of substitution by –NO2 group was impressive, when, the dyes ionization potential photon energy values reached to 5.58, 5.82, 5.83 and 6.07 eV. According to X-ray diffraction, dyes were not amorphous and value of crystallite size was ∼100 nm. The dyes have a promising application as a hole layer in dye sensitized solar cells (DSSCs), due to the separation distribution of HOMO-LUMO, thermal stability, small crystal size, high PLQY, high optical band gap and high electron affinity. Finally, the DSSCs devices were fabricated based on the synthesized dyes and the results showed that the efficiency of the DSSCs based on a dye with –NO2 group is higher (3.27%) than that of the other dyes.

Photoionization, Structures, and Energetics of Na-Doped Formic Acid-Water Clusters.

The influence of formic acid on water cluster aggregation has been investigated experimentally by mass spectrometry and tunable UV laser ionization applied to Na‐doped clusters formed in the supersonic expansion of water vapors seeded with formic acid (FA) as well as theoretically using high level quantum chemistry methods. The mass spectra of Na−FA(H2O)n clusters show an enlarging of mass distribution toward heavier clusters with respect to the Na−(H2O)n clusters, suggesting similar mass distribution in neutral clusters and an influence of formic acid in water aggregation. Density functional theory and coupled‐cluster type (DLPNO‐CCSD(T)) calculations have been used to calculate structures and energetics of neutral and ionized Na−FA(H2O)n as well as neutral FA(H2O)n. Na‐doped clusters are characterized by very stable geometries. The theoretical adiabatic ionization potential values match pretty well the measured appearance energies and the calculated first six electronic excited states show Rydberg‐type characters, indicating possible autoionization contributions in the mass spectra. Finally, theoretical calculations on neutral FA(H2O)n clusters show the possibility of similarly stable structures in small clusters containing up to n=4–5 water molecules, where FA interacts significantly with waters. This suggests that FA can compete with water molecules in the starting stage of the aggregation process, by forming stable nucleation seed.

Calculation of the ionization potential of zinc and graphene phthalocyaninates on the surface of dielectrics

A mathematical model is proposed for calculating the ionization potentials of molecules on the surface of dielectrics in order to quantify changes in the electronic characteristics of materials on a substrate. The semiconductor and photoelectronic properties of nanosystems based on phthalocyanine derivatives are determined by the electronic structure of molecules. Based on the zinc phthalocyaninate molecule ZnC32N8H16, model structures are constructed that increase this molecule by attaching benzene rings ZnC48N8H24, ZnC64N8H32 and a model simulating the film structure of Zn4C120N32 H48. Graphene was considered as a nanostructure modeling a fragment of a monomer lm. The ionization potentials of these compounds on the surface of magnesium oxide, sodium chloride and silicon are calculated. In the presence of a substrate, the ionization potentials of all nanostructures decrease, while the values of the surface ionization potentials remain fundamentally dierent in their magnitude for all compounds. The compound ZnC64N8H32 sprayed onto the surface exhibits the best photoelectronic properties, its surface ionization potential is comparable to graphene.

Theoretical study of new promising conjugated psoralens in psoralen ultraviolet A therapy

AbstractIn our previous report (J. Phys. Org. Chem., 2019), we discussed novel silicon photosensitizers (PSs) in psoralen ultraviolet A (PUVA) therapy. Continuing this quest, we have scrutinized a new brand of PSs, via density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) methods. These PSs show intense narrow absorption peaks in the therapeutic window with very high molar absorption coefficients ( ). Calculated vertical ionization potential (VIP) and vertical electron affinity (VEA) values indicate that our PSs can produce reactive oxygen species (ROS) through type I mechanism. Also, energies of the first triplet excited states (T1) and spin–orbit coupling (SOC) constants verify the possibility and efficiency of type II mechanism for the generation of the singlet excited state of molecular oxygen (1O2). The results introduce new potential PSs in PDT and PUVA therapy.

Pyrolysis-Free Oxygen Reduction Reaction (ORR) Electrocatalysts Composed of Unimolecular Layer Metal Azaphthalocyanines Adsorbed onto Carbon Materials

The oxygen reduction reaction (ORR) at the cathode is one of the critical bottlenecks in the energy conversion process in polymer electrolyte fuel cells (PEFCs) and metal–air batteries. An iron azaphthalocyanine unimolecular layer (Fe-AZUL) adsorbed onto a carbon substrate exhibited high ORR activity as an alternative of Pt supported on carbon black (Pt/C) electrocatalyst. We herein report the synthesis of various AzPc molecules with different peripheral structures and complex metals, as well as measurements of the ORR activities of catalysts containing the synthesized molecules and carbons. The catalytic activities were characterized by electrochemical analysis, density functional theory (DFT) calculations, and measurements of ionization potential (IP) values. From the results, the IP values on Ketjen Black (KB) were found to be one of the significant indicators for high ORR activities, providing a guideline for the development of high-performance electrocatalysts.

Adsorption of metformin on graphitic carbon nitride functionalized with metals of group 1–3 (Li, Na, K, Be, Mg, Ca, B, Al, and Ga), DFT calculations

Metformin is one of the important anti-diabetic drugs. DFT calculations have been performed to study properties of adsorption of metformin onto [M/g-C3N4]+,+2,+3, where M: Li, Na, K, Be, Mg, Ca, B, Al, and Ga. Optimized structures of all systems were calculated using the ONIOM computational method. The results were used to calculate the absorption energy (Eads) with the PBE0-D3(BJ)/def2-TZVP method. The adsorption energy values for the most stable configurations are 19.1–131.6 kcal/mol. By adsorption of metformin on [M/g-C3N4]+,+2,+3 surfaces, the ionization potential values of [M/g-C3N4]+, M: Li, Na and K are low, which means that the stability of M: Li, Na and K systems are higher than the other systems (groups 2 and 3). The [M/g-C3N4]+ complexes have been seen as interesting adsorbents of metformin molecule.

Rational Design and Characterization of Symmetry-Breaking Organic Semiconductors in Polymer Solar Cells: A Theory Insight of the Asymmetric Advantage.

Asymmetric molecule strategy is considered an effective method to achieve high power conversion efficiency (PCE) of polymer solar cells (PSCs). In this paper, nine oligomers are designed by combining three new electron-deficient units (unitA)—n1, n2, and n3—and three electron-donating units (unitD)—D, E, and F—with their π-conjugation area extended. The relationships between symmetric/asymmetric molecule structure and the performance of the oligomers are investigated using the density functional theory (DFT) and time-dependent density functional theory (TD–DFT) calculations. The results indicate that asymmetry molecule PEn2 has the minimum dihedral angle in the angle between two planes of unitD and unitA among all the molecules, which exhibited the advantages of asymmetric structures in molecular stacking. The relationship of the values of ionization potentials (IP) and electron affinities (EA) along with the unitD/unitA π-extend are revealed. The calculated reorganization energy results also demonstrate that the asymmetric molecules PDn2 and PEn2 could better charge the extraction of the PSCs than other molecules for their lower reorganization energy of 0.180 eV and 0.181 eV, respectively.

ANTI-OXIDANT AND ANTI-INFLAMMATORY POTENTIAL OF SECONDARY METABOLITES FROM Daphne mucronata ROYLE AND THEIR FIRST-PRINCIPLES INVESTIGATIONS

Ten coumarin class of compounds, including new fused coumarinolignoids namely, mucronin-C (1) were isolated from the methanol extract from whole plant of Daphne mucronata Royle. The structures of mucronin-C (1) and its configurations were determined by chemical and spectroscopic methods including 1DNMR, 2D-NMR and HR-FAB-MS. The isolated compounds 1-10 were evaluated for in-vitro biological activities. The anti-inflammatory (lipoxygenase) activities of compound 1, 4, 8, 9 and 10 (IC50 = 21.7, 23.7, 25.1, 27.3 and 26.0 µg/mL, respectively) were higher compared with standard Quercetin (IC50 = 22.5 µg/mL). The antioxidant property of coumarin as evaluated by DPPH scavenging bioassay was significantly greater in compounds 1-5, 9 and 10 (IC50 = 0.7, 0.8, 1.9, 2.3, 2.8, 0.5 and 2.1 µg/mL respectively) as standard Trolox (IC50 = 0.3 µg/mL). The density functional descriptors in the progress of quantitative structure-activity relationship (QSAR) are significant to analyze the reactive sites and antioxidant ability of compounds. We have explored the reactive sites and radical scavenging activity of studied coumarin derivatives by shedding light on electron affinity, ionization potential, molecular electrostatic potential, frontier molecular orbitals and molecular descriptors analysis. First-principles calculations about one-electron transfer mechanism revealed that smaller ionization potential value of Compounds 1-5, 9 and 10 are leading to superior antioxidant activity, which is in good agreement with the experimental data.

Exploration of electronic properties, radical scavenging activity and QSAR of oxadiazole derivatives by molecular docking and first-principles approaches.

Eight new oxadiazole derivatives were designed then geometries for ground state were optimized through Density Functional Theory (DFT) at B3LYP/6-31G** level. Single electron transfer mechanism has been studied to understand the antioxidant ability of the oxadiazole derivatives. Then molecular electrostatic potential and quantitative structure–activity relationship (QSAR) was probed. Additionally, we shed light on different molecular descriptors, e.g., electrophilicity(ω), electronegativity(χ), electrophilicity indices(ωi), hardness(η), softness(S) and chemical potential(μ).The smaller value of ionization potential for 5a is showing that it might be efficient antioxidant candidate. The electrophilic reactive sites in 2a, 3a, 4a, 5a and 7a derivatives might be a good choice for reactivity that would be advantageous to improve the biological activity. The polar surface area of 3a, 4a and 5a derivatives was found < 60 A2 which is enlightening that these drugs might be suitable as orally active and for brain penetration. First-principles calculations and molecular docking results revealed that 5a would lead to superior antioxidant activity.

Mechanochromic and thermally activated delayed fluorescence dyes obtained from D–A–D′ type, consisted of xanthen and carbazole derivatives as an emitter layer in organic light emitting diodes

In this study, we designed, engineered and investigated two new thermally activated delayed fluorescence (TADF) dyes obtained from D–A–D′ type, consisted of 2-(9H-carbazol-9-yl)-3-(3-methoxy-9H-carbazol-9-yl)-9H-xanthen and 2-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3-(3-methoxy -9H-carbazol-9-yl)-9H-xanthen. In these dyes, xanthen derivative and carbazole derivatives have played important roles as an acceptor and two unsymmetrical donor units. In addition, the photophysical properties of these dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay lifetime analysis in solution, initial dye, non-doped and doped solid state (neat–film) at different temperatures and under the vacuum-ambient. Substitution's strong effect of the donor units was impressive; where, the dyes' ionization potential values were achieved as 5.53 and 5.62 eV. The charge mobility measurements of dyes were carried out using two different methods of spacecharge–limited current (SCLC) and time of the flight (TOF). Appropriate extracted results proved dyes' promising application as an emitter layer in organic light emitting diodes (OLEDs), through the photophysical properties, aggregation induced emission enhancement (AIEE) phenomenon, and high intensity of emission spectrum spanning the large part of visible area and good thermal stability. The solution process and physical evaporation deposition (PVD) procedure were tandemly performed in order to coat the layers and fabricate non-doped and doped OLEDs. The low turned on voltage' values of OLEDs were recorded in the range of 4.08 to 5.31 V. Furthermore, the maximum values of brightness, current, power and external quantum efficiency were achieved as 72565 cd/m2, 37.32 cd/A, 20.99 lm/W and 13.41%, respectively.

Modulation of charge transfer and π-π interaction toward tunable fluorescence emission in binary cocrystals composed of carbazole derivatives and 1,2,4,5-tetracyanobenzene

Herein, with the targeted aim of constructing binary complex with tunable fluorescence emission, a series of novel charge transfer (CT) cocrystal C1–C4 are designed and synthesized via facile solution-processing approach by selecting carbazole derivatives 9-(4-bromophenyl)carbazole (BrCz), N-methylcabazole (MeCz), 1,4-di (carbazole-9-yl)benzene (DCB), 5,7-dihydro-7,7-dimethylindeno [2,1-b]carbazole (InCz) as donors (D) and 1,2,4,5-tetracyanobenzene (TCNB) as acceptor (A). The π-conjugation property and configuration factor of donors are considered to regulate the CT driving force and π-π interaction within cocrystals. Structural and optical analysis, as well as theoretical calculations are accomplished to investigate the as-resulting products. As expected, donor's larger π-moiety accompanied with lower ionization potential (IP) value and planar configuration that promotes to stronger π-π interaction, are beneficial to enhance CT degree, thus endowing corresponding cocrystals with longer emission wavelength. Therefore, C1–C4 realize tailorable fluorescence emission with donor-dependent features covering a wide range from 582 nm to 642 nm. The investigation not only provides a platform to understand the structure-fluorescence relationship, but also gives instructions to readily achieve tunable emission behavior by selecting suitable D/A individual component via CT cocrystal method.