First principles investigations of electronic, photoluminescence and charge transfer properties of the Naphtho[2,1-b:6,5-b′]difuran and its derivatives for OFET

We have designed new derivatives of naphtha [2,1-b:6,5-b′] difuran as DPNDF-CN1 and DPNDF-CN2. The molecular structures of DPNDF, its derivatives DPNDF-CN1 and DPNDF-CN2 have been optimized at the ground (S0) and first excited (S1) states using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. Then the highest occupied molecular orbitals (HOMOs), the lowest unoccupied molecular orbitals (LUMOs), photoluminescence properties, electron affinities (EAs), reorganization energies (λs) and ionization potentials (IPs) have been investigated. The balanced λ(h) and λ(e) showed that DPNDF, DPNDF-CN1 and DPNDF-CN2 would be better charge transport materials for both hole and electron. The effect of attached acceptors on the geometrical parameters, electronic, optical and charge transfer properties have also been investigated

The structural, electro-optical, charge transport and nonlinear optical properties of oxazole (4Z)-4-Benzylidene-2-(4-methylphenyl)-1,3-oxazol-5(4H)-one derivative

The oxazole compounds are being used for multifunctional purposes ranging from organic light emitting diodes, organic thin film transistors, and photovoltaic to the nonlinear optical materials. In this study, several structural, electro-optical, charge transport and nonlinear optical properties of (4Z)-4-Benzylidene-2-(4-methylphenyl)-1,3-oxazol-5(4H)-one (BMPO) have been investigated. Density functional theory (DFT) and time dependent DFT are very accurate and reasonable approaches to optimize the ground and excited state geometries, respectively. Thus, in the present study DFT and TDDFT methods with the B3LYP/6-31G∗∗ levels of theory have been applied to shed some light on the structure-property relationship, frontier molecular orbitals (FMOs), optical properties. A clear intra-molecular charge transfer (ICT) from the highest occupied molecular orbitals (HOMOs) to the lowest unoccupied molecular orbitals (LUMOs) has been observed. The ionization potentials (IP), electron affinities (EA), total and partial densities of states have been discussed intensively. The electron reorganization energy of oxazole compound (BMPO) is smaller than the hole reorganization energy revealing that it might be good electron transport contender in OLED. The electron reorganization energy of BMPO is calculated to be 0.223 eV that is smaller than the perfluoropentacene (value is 0.250 eV), which is famous n-type semiconductor material. The first pathway of BMPO has almost comparable hole and electron transfer integral values whereas the calculated electron reorganization energy (0.223 eV) is considerably lower than the hole reorganization energy (0.381 eV) which leads to superior electron intrinsic mobility of the studied oxazole derivative as compared to the hole one. It is expected that BMPO might be excellent electron transport material

Effects of electron withdrawing groups on transfer integrals, mobility, electronic and photo-physical properties of naphtho[2,1-b:6,5-b ']difuran derivatives: a theoretical study

New derivatives of naphtho[2,1-b:6,5-b ]difuran (DPNDF) have been designed by attaching different electron withdrawing groups (EWGs) (including –COOH, –OCF3 and –CN). The molecular structures of all derivatives have been optimized at the ground (S 0) and first excited (S 1) states using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively. The highest occupied molecular orbitals (HOMOs), the lowest unoccupied molecular orbitals (LUMOs), photophysical properties, adiabatic/vertical electron affinity (EAa)/(EAv), adiabatic/vertical ionization potential (IPa)/(IPv) and hole/electron reorganization energies λh/λe have been investigated. Transfer integral, mobility and stability have also been calculated. Electron mobility as high as 5.148 cm2 V–1 s–1 has been obtained. Upon substituting the EWGs electron transfer integrals are boosted in newly designed derivatives. The balanced hole and electron reorganization energies, and the improved transfer integrals lead to enhanced mobility in the derivative with COOH groups. Thus the latter compound would be an efficient electron transfer material. Photo-stability of furan based materials is enhanced by introducing the EWGs at different positions

Computational investigation of electronic and optical properties of spinal sulfides Sc2XS4 (X= Zn, Mg and Be) for photovoltaic and solar cell applications

Using the computational techniques, the cubic structure of spinel sulfides Sc2XS4 (X = Zn, Mg, and Be) were investigated for electronics, structural and optical properties. We evaluated the lattice parameter “a”, total density of state (DOS) and optical properties by the full-potential linearized augmented plane wave (FP-LAPW) method within the background of density functional theory (DFT) through the generalized gradient approximation (GGA). The Trans-Blaha modified Becke Johnson (TB-mBJ) potential approximation has been utilized to calculate the electronic bandgap as it is considered a good approach to reproduce the energy gap more accurately. The profile of electronic band structures disclosed the direct bandgaps of the magnitude 1.62, 2.30, and 1.60 eV for Sc2ZnS4, Sc2MgS4, and Sc2BeS4, respectively. Similarly, these materials display decent absorption and reflectivity in the UV region of light revealing the potential of these spinal sulfides as a shield against UV radiations. Our computed results of electronic and optical properties recommend that the studied spinel sulfides Sc2XS4 (X = Zn, Mg, and Be) would be suitable for photovoltaic and solar cell applications

Exploring the opto-electronic and charge transfer nature of F-BODIPY derivatives at molecular level: A theoretical perspective

The goal of current work is to investigate the effect of ethyl group on the electronic, photo-physical and charge transport properties of F-BODIPY, which has been explored at the molecular level after substituting ethyl group at two position of F-BODIPY molecule. In current study; optical, electronic and charge transfer properties for F-BODIPY derivatives (Comp_1, Comp_2 and Comp_3) have been theoretically investigated. All the molecules have been optimized at the ground (S0) and first excited (S1) states using density functional theory (DFT) and time dependent DFT (TD- DFT) with the hybrid functional/basis set (B3LYP /6-31G**), respectively. Effect of ethyl groups at two different positions on the electronic, optical and charge transport properties of 5,5-difluoro-1,37,9-tetramethyloctahydro-1H,5H-514-dipyrrolo[1,2-c:2′,1′-f] [1–3] diazaborinine (Comp_1) as parent molecule has been studied at molecular level. The introduction of ethyl at two positions in Comp_1 led to a red shifted absorption spectra in comparison with parent molecule in the violet region. Various properties of interest such as highest occupied molecular orbitals (HOMO), lowest unoccupied molecular orbitals (LUMO), vertical electron affinity (EAv), adiabatic electron affinity (EAa), vertical ionization potential (IPv), adiabatic ionization potential (IPa), electron reorganization energies (λe) and hole reorganization energies (λh) were explored. Additionally, global reactivity descriptors e.g. electronic chemical potential (μ), electronegativity (χ), Electrophilicity (ω), hardness (η), softness (S) and electrophilicity index (ωi) have been calculated theoretically

Investigating the effect of acene-fusion and trifluoroacetyl substitution on the electronic and charge transport properties by density functional theory

We designed novel derivatives of 4,6-di(thiophen-2-yl)pyrimidine (DTP). Two benchmark strategies including mesomerically deactivating group, as well as the extension of π-conjugation bridge (acene-fusion) have been employed to enhance the electrical and charge transport properties. The density functional theory (DFT) and time dependent DFT methods have been used to get optimized geometries in ground and first excited state, respectively. The structural properties (geometric parameters), electronic properties (frontier molecular orbitals; highest occupied and lowest unoccupied molecular orbitals), photophysical properties (absorption, fluorescence and phosphorescence), and important charge transport properties are discussed to establish a molecular level structure–property relationship among these derivatives. Our calculated electronic spectra i.e., absorption, fluorescence and phosphorescence have been found in good semi-quantitative agreement with available experimental data. All the newly designed derivatives displayed significantly improved electron injection ability than those of the parent molecule. The values of reorganization energy and transfer integral elucidate that DTP is a potential hole transport material. Based on our present investigation, it is expected that the naphtho and anthra derivatives of DTP are better hole transporters than those of some well-known charge transporter materials like naphthalene, anthracene, tetracene and pentacene

Influence of push-pull configuration on the electro-optical and charge transport properties of novel naphtho-difuran derivatives: a DFT study

We present a density functional theory (DFT) study pertaining to electro-optical and charge transport properties of two novel derivatives of diphenyl-naphtho[2,1-b:6,5-b′]difuran (DPNDF) as investigated based on push-pull configuration. Both molecular structures of the designed derivatives were optimized, in ground state (S0) as well as excited state (S1), using DFT and time-dependent DFT (TD-DFT) respectively. The push-pull configuration effect was studied meticulously for different electro-optical properties including adiabatic/vertical electron affinity (EAa/EAv), adiabatic/vertical ionization potential (IPa/IPv) and hole/electron reorganization energies (λh/λe), hole/electron transfer integrals (Vh/Ve), hole/electron mobility and photostability. We observed smaller λe, improved Ve and higher electron mobility for compound 1 compared with the parent molecule. Our calculated value of the electron mobility for compound 1 (2.43 cm2 V-1 s-1) revealed it to be an efficient electron transport material. Moreover, the influence of the push-pull on the electronic structure was also investigated by calculating the total and partial density of states (DOS). Taking advantage of the strong push-pull configurations effect on other properties, the study of the designed chemical systems was extended to their nonlinear optical (NLO) properties. Our designed novel derivatives (1 & 2) exhibited significantly larger amplitude values for first hyperpolarizability with βtot equal to 209.420 × 10-30 esu for compound 1 and 333.830 × 10-30 esu for compound 2. It was found that the first hyperpolarizability and HOMO-LUMO energy gap are in an inverse relationship for compounds 1 and 2

Thermoelectric properties of the novel cubic structured silicon monochalcogenides: A first-principles study

The low-cost and non-toxic candidates of the Group-IV monochalcogenide family have attracted significant attention in recent years for large-scale thermoelectric applications. We conduct comprehensive investigations of the thermoelectric response of relatively inexpensive and less toxic cubic structured Si-monochalcogenides (π-SiS, π-SiSe, and π-SiTe) for renewable energy applications. The full-potential linearized-augmented-plus-local-orbital method within density functional theory has been adopted to calculate the ground state energies, whereas the semi-classical Boltzmann transport theory has been used for the calculations of thermoelectric properties. The Si-monochalcogenides in cubic phase demonstrate large values of thermopowers that amounts to 1740.0 μV/K, 1405.0 μV/K, and 771.92 μV/K of the π-SiS, π-SiSe, and π-SiTe respectively at 300 K. The thermopowers show an insignificant response to increase in temperature which is beneficial for the high-temperature thermoelectric applications of these materials. The optimal values of thermoelectric power factors of the cubic structured Si-chalcogenides occur at attainable doping levels and have been originated from the joint contribution of moderate electrical conductivities and thermopowers. These materials demonstrate the figure of merit values approaching unity and have shown a trivial response to the temperature gradient. Moreover, the occurrence of the optimal values of thermoelectric coefficients for electrons doped regime suggests the n-type doping as an easy option for enhancing the thermoelectric performance of these materials. Our investigations show that the Si-monochalcogenides in cubic phase feature interesting thermoelectric performance and can be used as a suitable replacement for the toxic and expensive binary chalcogenides for thermoelectric applications

Electro-optical and charge injection investigations of the donor-π-acceptor triphenylamine, oligocene–thiophene–pyrimidine and cyanoacetic acid based multifunctional dyes

The corner stone of present study is to tune the electro-optical and charge transport properties of donor-bridge-acceptor (D-π-A) triphenylamine (TPA) derivatives. In the present investigation, an electron deficient moiety (pyrimidine), electron-rich moiety (thiophene) and oligocene (benzene, naphthalene, anthracene, tetracene and pentacene) have been incorporated as π-spacer between the donor TPA unit and cyanoacetic acid acceptor and anchoring group. The elongation of bridge usually affects the energy levels, i.e., higher the highest occupied molecular orbital (HOMO) while lower the lowest unoccupied molecular orbital (LUMO) thus reduces the HOMO–LUMO energy gap. The lowered LUMO energy levels of cyano-{2-[6-(4-diphenylamino-phenyl)-pyrimidin-4-yl]-tetraceno[2,3-b]thiophen-8-yl}-acetic acid (TPA-PTT4) and cyano-{2-[6-(4-diphenylamino-phenyl)-pyrimidin-4-yl]-pentaceno[2,3-b]thiophen-9-yl}-acetic acid (TPA-PPT5) dyes revealed that electron injected from dye to semiconductor surface might be auxiliary stable resulting in impediment of quenching. The broken co-planarity between the π-spacer conceiving LUMO and the TPA moiety would help to impede the recombination process. Moreover, it is expected that TPA derivatives with the tetracenothiophene and pentacenothiophene moieties as π-bridge would show better photovoltaic performance due to lowered LUMO energy level, higher electronic coupling constant, light harvesting efficiency and electron injection values

Effect of donor strength of extended alkyl auxiliary groups on optoelectronic and charge transport properties of novel naphtha[2,1-b:6,5-b′]difuran derivatives: simple yet effective strategy

The present study spotlights the designing of new derivatives of 2,7-bis (4-octylphenyl) naphtho [2,1-b:6,5-b'] difuran (C8-DPNDF) by substituting the alkyl groups (methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl groups) at para position. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods are employed to optimize the molecular structures in ground and first excited states, respectively. Several electro-optical properties including hole/electron reorganization energies (?h/?e), electron affinities (EAs), ionization potentials (IPs), molecular electrostatic potentials (MEP), and frontier molecular orbitals (FMOs) have been evaluated. Furthermore their transfer integrals and intrinsic mobilities values have also been calculated. From this study, it is found that hole mobility of octyl containing derivative is raised to 4.69 cm2 V-1 s-1. Moreover with attaching octyl group, hole transfer integral values have also been enhanced in newly designed derivatives. The balanced hole and electron reorganization energies, and improved transfer integrals lead to enhanced mobility in derivatives with octyl group, highlighting them as an efficient hole transfer material. Unlike the other electro-optical properties, the intrinsic hole mobility has increased because of transfer integral values of octyl containing derivative C8-DPNDF due to the dense and close crystal packing of C8-DPNDF. However, photostability of furan-based materials has not changed by increasing length of extended alkyl chain. Thus our present investigation highlights the importance of alkyl auxiliary groups that are often neglected/replaced with simple methyl group to save computation costs