Optical Properties and Light-Induced Charge Transfer in Selected Aromatic C60 Fullerene Derivatives and in Their Bulk Heterojunctions with Poly(3-Hexylthiophene) (original) (raw)
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In this research, the C50 fullerene was employed as the source of the π electrons and the electron donor-acceptor groups were used to enhance its optical properties. Considerable enhancement in its electronic and optical property of as the result of donor and acceptor group presence was observed. For instance, in UV-Visible absorption spectrum, the number of absorption lines significantly increase which may be the relaxation of the electronic transition selection rules. Considerably, the substituted forms of C50, has numbers of absorption bands in near infrared region. The BH2-C50-NCH3Li and NO-C50-NCH3Li molecules have superior improvement in optical properties. Finally, the donor and acceptor groups influence on non-linear optical properties (NLO) of C50 were explored and the considerable improvement in NLO properties of C50 was observed which the NLO improvements for BH2-C50-NCH3Li and NO-C50-CH2Li cases is higher than others.
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In the present work, we report the successful synthesis and characterization of six (two new) fullerene mono- and di-pyrene derivatives based on C60 and C70 fullerenes. The synthesized compounds were characterized by spectral methods (ESI-MS, 1H-NMR, 13C-NMR, UV-Vis, FT-IR, photoluminescence and photocurrent spectroscopy). The energy of HOMO and LUMO levels and the band gaps were determined from cyclic voltammetry and compared with the theoretical values calculated according to the DFT/B3LYP/6-31G(d) and DFT/PBE/6-311G(d,p) approach for fully optimized molecular structures at the DFT/B3LYP/6-31G(d) level. Efficiency of solar cells made of PTB7: C60 and C70 fullerene pyrene derivatives were analyzed based on the determined energy levels of the HOMO and LUMO orbitals of the derivatives as well as the extensive spectral results of fullerene derivatives and their mixtures with PTB7. As a result, we found that the electronic and spectral properties, on which the efficiency of a photovolt...
The Study of the Optical Properties of C60 Fullerene in Different Organic Solvents
Open Chemistry, 2019
C60 fullerene exhibits unique optical properties that have high potential for wide photo-optical applications. To analyze the optical properties of C60, its excitation and emission properties were studied using UV-Vis absorption and photoluminescence (PL) spectroscopy, which were performed in various, non-polar organic solvents such as toluene, xylene, and trichloroethylene (TCE). The C60 solutions in toluene, xylene, and TCE displayed similar excitation bands at 625, 591, 570, 535, and 404 nm corresponding to Ag → T1u and Ag → T1g transitions. However, these bands differed from the solid C60 observed by UV-Vis diffuse reflectance spectroscopy. The two emission band energies of C 60 solution in toluene and xylene were nearly the same (1.78 and 1.69 eV), whereas the C60 solution in TCE was shifted to 1.72 and 1.65 eV. Because the polarity of TCE is higher than that of toluene and xylene, the PL spectrum of the C 60 solution in TCE was red-shifted. The PL spectroscopy had a better cap...
Journal of the American Chemical Society, 1995
A covalently functionalized fullerene comprising an electron donating aniline group coupled to the fullerene unit by a saturated heterocyclic bridge is shown to undergo a photoinduced intramolecular electron transfer process that causes quenching of the fluorescence of the adduct and strong decrease of triplet population in polar solvents. VIS-absorption, fluorescence and phosphorescence at 77 K, triplet-triplet absorption, time resolved fluorescence, and redox potentials of the fullerene adduct are presented. Analysis of the solvent dependence of the energetics of the intramolecular electron transfer is given and is in good agreement with the experimental results.
Photophysical Properties of a 1,2,3,4,5,6-Hexasubstituted Fullerene Derivative
The Journal of Physical Chemistry A, 2006
The photophysical properties of a novel 1,2,3,4,5,6-hexasusbstituted fullerene derivative (1) are examined in this study. In addition to the ground state absorption spectrum of 1 we report its triplettriplet absorption spectrum and molar extinction coefficient (Δε T-T ), as well as the triplet quantum yield (Φ T ), lifetime (τ T ), and energy (E T ). The saturation of a single six-member ring on the fullerene cage results in significant changes in the triplet state properties as compared to that of pristine C 60 . The triplet-triplet absorption spectrum shows a hypsochromic shift in long wavelength absorption and both the triplet state lifetime and triplet quantum yield are decreased. The triplet energy was found to be similar to that of C 60 . In addition, the quantum yield (Φ Δ ) of singlet oxygen generated by 1 was calculated and is found to be significantly less than in the case of C 60 .
Journal of Molecular Structure, 2006
A detailed UV-Vis spectrophotometric, thermodynamic and NMR studies have been carried out to look insight into the nature of molecular interactions of the electron donor-acceptor complexes of [60]fullerene with three different polycyclic aromatic hydrocarbon (PAH) molecules in CCl 4 medium. Well defined charge transfer (CT) absorption bands have been located in the visible region. We extract degrees of charge transfer, oscillator and transition dipole strengths by analyzing the transition energy of the CT band as a function of vertical ionization potentials of the donors studied. The influences of the PAH on the absorption spectrum of [60]fullerene are studied. The experimental results have been explained using a theoretical model that takes into account the interaction between electronic subsystems of PAH with [60]fullerene. Formation constants (K) of the [60]fullerene/PAH complexes are determined spectrophotometrically (utilizing Benesi-Hildebrand equation) at four different temperatures and by 1 H NMR spectroscopic technique. Trend in the formation constant values for the [60]fullerene/PAH complexes are discussed in terms of enthalpies and entropies of formation. Free energies of formation values for the [60]fullerene/PAH systems as well as ab initio calculation suggest that nature of substitution and steric effect in the PAH systems play vital role in formation of EDA complexes with [60] fullerene.
Advanced Functional Materials, 2009
Synthesis of a new symmetrical 1,4,8,11,15,18,22,25-octahexyloxy-2,3,9,10,16,17,23,24-octa-(3,5-dichlorophenyl)phthalocyaninato zinc(II), ZnPc, has been described and characterized by 1 H NMR, 13 C NMR, MS, UVeVis, and IR spectrometry. The newly prepared ZnPc is soluble in organic solvents and is not aggregated in solution. The photophysical properties were studied by steady-state absorption and emission, cyclic voltammetry, and nanosecond transient absorption techniques. The prepared ZnPc absorbs and emits at longer wavelengths compared to that of reported phthalocyanine derivatives. The electron-donating properties of the ZnPc have been examined by mixing it with the electron-accepting dicyanoperylene-3,4,9,10-bis(dicarboximide), PDICN 2 . The recorded nanosecond transient spectra in the visible/near-IR region showed clearly the electron-transfer from the triplet-excited state of the ZnPc to PDICN 2 with a rate of 3.40 Â 10 8 M À1 s À1 . Light absorption in a wide section of the solar spectrum, favorable redox properties, and the electron-transfer properties suggest usefulness of the ZnPc in lightenergy harvesting and developing optoelectronic devices.
Solar Energy Materials and Solar Cells, 2012
A quantum chemical computational study has been performed at B3LYP/6-311G(d, p) level to investigate electronic structures of the C60 and C70 fullerene derivatives, as electron acceptor in bulk heterojunction solar cells, seeking ways to improve their efficiency in corresponding photovoltaic devices. The key point of the present survey is to achieve a significant linear correlation between the electrophilicity index calculated for the fullerene derivatives and the corresponding open-circuit voltage of the photovoltaic device. This index is a prominent feature in determining tendency of the fullerene derivative towards acquiring an additional electron from the adjacent electron-rich donor molecule, and also its resistance to give the electron back transfer. The results reveal that replacing butyric acid ester by propionic acid ester in the aliphatic part or increasing the donating strength of the substituent in the esteric part will cause an increase in electrophilicity. Considering the derivatives of C70 generally yields higher electrophilicity than those of C60 derivatives. Also for indene-C60 derivatives a significant increase in the electrophilicity is observed by increasing the number of adducts, leading to raise in the V OC values.