Theoretical investigation of new organic materials based on fluorene and thiophene for photovoltaic applications

In this study, five compounds of novel acceptor-donor organic materials containing 9,9-d imethyl-9H-fluoren, (2,5) dimethyloxy-4-(thiophen-2yl) thiophene linked to cyanoacrylic acid via several dyes  based alternating donors are investigated. The geometries, electronic absorption and emission spectra of these six compounds are studied by Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD/DFT) calculations. The HOMO, LUMO, Gap energy, λmax, Voc of these compounds have been calculated and reported in this paper. The objective of this study; is to evidence the relationship between chemical structure of these organic materials and their properties optoelectronic of ways has conceive thereafter the compounds with effective character for solar cells.

Materials Based on Carbazole for Organic Solar Cells Applications. Theoretical Investigations

The research in new organic π-conjugated molecules with specific properties has become one of the most interesting topics in fields of materials chemistry. These materials are promising for optoelectronic device technology such as solar cells. On the other hand, the use of low band gap materials is a viable method for better harvesting of the solar spectrum and increasing its efficiency. The Control of this parameter is essential to predict and study the electronic parameters for possible applications in optoelectronics. In this work, quantum chemical investigations have been performed to explore the optical and electronic properties of two compounds based on carbazole. Firstly, we have determined the effect of grafting the Fluorine atoms on their opto-electronic and physico-chemical properties. In addition to the solubility in the polar solvents and the modification in geometric parameters, the substitution of Fluorine destabilize the HOMO and LUMO levels, decreases the band gap energy and raises conjugation length. Electronic, optical and photovoltaic properties have been reported in order to predict the BHJ solar cell device efficiency for studied compounds

Design and photovoltaic properties of new molecules based bithiophene for bulk heterojunction solar cells

In the present work, new π-conjugated compounds based on bithiophene have been studied by quantum chemistry using DFT (Density Functional Theory) at B3LYP/6-31G(d,p) level to examine the structural and electronic properties. The absorption spectra were simulated by TD-DFT (Time Dependent Density Functional Theory) at the same level.The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of these compounds were calculated and compared to LUMO of fullerenes C60. Electronic, optical and photovoltaic properties have been reported in order to predict the BHJ solar cell device efficiency for studied compounds

Elaboration, Thermal and Structural Approach of Manganese Phosphate Glasses Inside the System of K2O-MnO2-P2O5

Glasses of the composition (50-x/2) K2O-xMnO(2)-(50-x/2) P2O5 with (0 <= x <= 30%mol), have been prepared by standard melt quenching procedures. The amorphous state of the glasses is evidenced using the X-Ray diffraction. Their physical properties were characterized by thermal analysis and density measurements. The density and the glass transition temperature increase with increasing in MnO2 content. To study the structural role of MnO2 oxide in studied glasses, the FTIR and Raman spectroscopies have been employed. It was highlighted that the presence of MnO2 allows the depolymerisation of the phosphate chains and formation of covalent bonds P-O-Mn, which replace P-O-P and P=O linkages

Electronic and photovoltaic properties of new materials based on imidazo[1,2-a]pyrazine. Computational investigations

A quantum chemical investigation has been performed to explore optical and electronic properties of a series of different compounds based π-conjugated molecular materials with fused rings, on imidazo[1,2-a]pyrazines. Different electron-donor side groups as side-chain substituents were introduced in molecular backbone to investigate their effects on the electronic structure. The HOMO and LUMO energy levels as well energy gap Eg of the studied compounds have been calculated and reported. The obtained data suggest that studied molecules are good candidates for organic solar cells

Thermal and structural studies of Li2O‐Na2O‐SrO‐TiO2‐B2O3‐P2O5 glasses by DTA, IR and EPR spectroscopy

Glasses in molar fraction in the system 33.33[xNa2O‐(1‐x)Li2O]‐2.5SrO‐2.5TiO2‐45B2O3‐16.67P2O5 (0.0 ≤ x ≤ 1.0) were prepared by standard melt quenching procedures, their physical properties were characterized by thermal analysis and density measurements. Their local structures were comprehensively characterized by Infrared spectroscopy (IR) and electron paramagnetic resonance (EPR). The variation of the glass transition temperature as a function of the glass compositions is non‐linear. The infrared spectroscopy of the glasses has identified the presence of different structural grouping units in the glassy‐matrix. It is found that the stretching and bending vibration modes of borate groups are more sensitive to the substitution of alkali elements. EPR experiments have shown the presence of Ti3+ centers in the glasses. The variation of the g‐factor as a function of the Na/(Na+Li) ratio presents a minimum around (x=0.5). The composition nonlinearity behavior of Tg, vibration bending mode, and g‐factor are signature of the mixed alkali effect in the glasses

Study of low band gap DSSCs based on bridging bithiophene and biphenyl: Theoretical investigation

International audienceIn this paper, theoretical study using density functional theory (DFT) method (B3LYP level with 6-31G(d,p)) of four novel low band gap acceptor-donor organic materials based on thiophene and phenyl and linked to cyanoacrylic acid as acceptor group are investigated. Different electron side groups were introduced to investigate their effects on the electronic structure; the HOMO, LUMO, gap energy, ionization potentials, electron affinities and open circuit voltage (V oc) of these compounds have been calculated and reported in this paper. The electronic absorption and emission spectra of these dyes are studied by time-dependent density functional theory calculations. A systematic theoretical study of such compound has not been reported as we know. Thus, our aim is first, to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations. We think that the presented study of structural, electronic and optical properties for these compounds could help in designing more efficient functional photovoltaic organic materials. © 2015 Iranian Chemical Society