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Synthesis and characterization of novel benzodithiophene-fused perylene diimide acceptors: Regulate photovoltaic performance via structural isomerism
摘要： Two isomeric benzodithiophene-fused perylene diimides, BPDI-1 and BPDI-2, are designed and synthesized via photo-induced ring-closure reaction between perylene diimide (PDI) acceptor and both isomeric benzodithiophene donor cores, including benzo[2,1-b:3,4-b']dithiophene (BDP) and benzo[1,2-b:4,3-b']dithiophene (BdT). The effect of structural isomerism on the molecular geometry, absorption, energy level, film morphology as well as photovoltaic performance is comparatively studied. It is found that the variation of the S atom substituted position in the donor cores results in distinct molecular geometries for the newly-developed BPDI-1 and BPDI-2 acceptors. Compared with BDP-containing BPDI-1, the incorporation of BdT core endows BPDI-2 with a remarkably enhanced backbone distortion. When blended with the commercially available polymer donor (PTB7-Th), such twisted structure feature for the BPDI-2 acceptor plays a key role in reducing molecule aggregation, which is helpful for the enhancements of short-circuit current density and photovoltaic efficiency effectively. As a result, non-fullerene solar cells fabricated from BPDI-2 acceptor achieve higher photovoltaic efficiency (4.44%) than that of BPDI-1 (2.98%), mainly benefited from superior short-circuit current density. This work provides us comparative understanding of isomeric geometry and device performance.
关键词： Benzodithiophene,Molecular geometry,Non-fullerene organic solar cells,Perylene diimide derivatives
更新于2025-11-19 16:56:42
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Enabling low voltage losses and high photocurrent in fullerene-free organic photovoltaics
摘要： Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron-deficient-core-based fused structure into non-fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short-circuit current density of 22.0 mA cm?2, resulting in high power conversion efficiencies of over 13.4%. These unconventional electron-deficient-core-based non-fullerene acceptors with near-infrared absorption lead to low non-radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.
关键词： non-fullerene acceptors,power conversion efficiency,voltage losses,charge separation,organic photovoltaics
更新于2025-11-14 15:18:02
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Structural and spectroscopic studies of bromofullerene
摘要： Structural and spectroscopic studies on fullerene and bromofullerene molecules were investigated. The reaction with liquid bromine was used to prepare bromofullerene and it was characterized by using X-ray diffraction, ultravioletevisible, Fourier transform infrared, Fourier transform Raman, electron paramagnetic resonance, scanning electron microscopy, high resolution transmission electron and energy dispersive X-ray techniques. The XRD pattern of bromofullerene con?rms the attachment of bromine to fullerene. FT-IR and FT-Raman characterization reveal the C-Br vibrations in the brominated fullerene which con?rms the bromination. UVeVis spectral analysis endorses shifting of absorption peak. EPR line width, with g-factor values, indicates the magnetic ion sites in the samples. Scanning electron microscope and high resolution transmission electron microscope signify the changes in surface and particle size of the molecule. The particle size was calculated from Debey-Sherrer's formula and corroborated by TEM images. Energy dispersive X-ray elemental micro analysis con?rms the presence of bromine element in the molecule. The enhanced reactivity by substitution of bromine paves the way for designing the bioactive molecules which will be useful in the ?eld of carbon nano-medicine and targeted drug delivery applications.
关键词： Bromination,HRTEM,Structure properties,Fullerene
更新于2025-11-14 15:16:37
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Study of the photoresponse of a titanium anode coated with solution-processed fullerene-containing metal porphyrin/phthalocyanine films
摘要： The present paper deals with the recent studies on the preparation of porphyrin-based donor-acceptor complexes capable of photoinduced electron transfer for solution-processed organic solar cells. Here the synthesis and chemical structure of (octakis(3,5-di-tert-butylphenoxy)phthalocyaninato) cobalt(II) (1) and (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(2-pyridyl)porphinato) manganese(III) chloride (2) are performed and self-assembly in toluene solution of 1 and 1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4′:1,2][60]fullerene (PyC60) were discussed in more details. The structure of the obtained dyad 1-PyC60 is con?rmed by means of chemical thermodynamics/kinetics, UV–vis, IR, 1H NMR spectroscopy. Photoelectrochemical studies of the phthalocyanine-fullerene dyad and its precursors were carried out by voltammetry and amperometry methods. A comparative analysis of the photoelectrochemical characteristics obtained in this paper and these for recent described cobalt(II)/manganese(III) porphyrin/phthalocyanine-fullerene dyads are introduced from which ideas for the future design of high performance organic solar cells will be developed.
关键词： donor-acceptor complexes,organic solar cells,phthalocyanine,photoinduced electron transfer,fullerene,porphyrin
更新于2025-11-14 15:14:40
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Distributed polarizability of fullerene [2+1]-adducts C60X (n?=?1 and 2) with symmetric addends?X??=?CH2 and O: A fresh view on the effect of positional isomerism
摘要： We have performed a site-specific analysis of the mean polarizability of fullerene [2+1]-adducts C60Xn (n = 1 and 2) with symmetric addends X = CH2 and O using the distributed polarizability model. We have found that the contributions from the fullerene core and addends to the molecular polarizability are not the same for different regioisomeric C60X2: the core contribution linearly decreases and the addend contribution linearly increases with the distance between the addends (or the functionalized bonds of the C60 cage). Additionally, the contributions are sensible to the degree of the fullerene core functionalization: the contribution of the C60 core decreases with the number of the attached addends due to reducing its π-electronic system.
关键词： isomerism,additive polarizability,polarizability,distributed polarizability,fullerene,fullerene adducts
更新于2025-09-23 15:23:52
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Study of the Electronic and Electrical Properties of the C60F18 Polar Molecule on Au(111) Surface
摘要： For adequate description of the adsorption and self-assembly of C60F18 polar molecules on the surface Au(111), quantum-chemical studies of the electronic and electrical properties of a single molecule are performed. Using various procedures of density functional theory, the electric dipole moment of the molecule, distributions of the electrostatic potential, electric-field magnitude and electron density are calculated with controlled accuracy for the first time. An improved value of the electric dipole moment of the C60F18 molecule is obtained in a range from 10 to 11 D. The known approximation of a point dipole for electric-field strength is shown to be fulfilled within an accuracy of 30% even at distances twice greater than the size of the molecule. The structural fragments of the calculated lowest unoccupied and highest occupied molecular orbitals are assigned to their images, which were previously obtained using scanning tunneling microscopy and spectroscopy.
关键词： density functional theory,lowest unoccupied and highest occupied molecular orbitals,electric dipole moment,scanning tunneling spectroscopy,fullerene fluoride
更新于2025-09-23 15:23:52
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Dispersion relations of elastic waves in three-dimensional cubical piezoelectric phononic crystal with initial stresses and mechanically and dielectrically imperfect interfaces
摘要： The shape of individual building blocks is an important parameter in bottom-up self-assembly of nano-structured materials. A simple shape change from sphere to spheroid can significantly affect the assembly process due to the modification to the orientational degrees of freedom. When a layer of spheres is placed upon a layer of spheroids, the strain at the interface can be minimized by the spheroid taking a special orientation. C70 fullerenes represent the smallest spheroids, and their interaction with a sphere-like C60 is investigated. We find that the orientation of the C70 within a close-packed C70 layer can be steered by contacting a layer of C60. This orientational steering phenomenon is potentially useful for epitaxial growth of multilayer van der Waals molecular heterostructures.
关键词： interface,self-assembly,epitaxy,scanning tunnelling microscopy,graphene,van der Waals heterostructures,fullerene
更新于2025-09-23 15:23:52
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Tuning the Spectrum Properties of Fullerene C60: Using a Strong External Electric Field
摘要： The electric ?eld can change the absorption of fullerene C60 to different wavelengths of light by affecting the vibrational modes and electronic transitions. The IR spectrum of fullerene C60 under the strong electric ?eld is studied on B3LYP/6-31G* basis set using density function theory. With the external electric ?eld decreasing, silent modes Hg(1), Ag(1), Gu(2), Hg(5), Ag(2), Hu(7) become active. Meanwhile, UV–Vis spectrum, the excitation energy, excitation wavelength and oscillator strength of ?rst fourteen excited states of fullerene C60 under the ?eld are also studied in B3LYP/6-31G* basis set using time-dependent density functional theory. With the electric ?eld increasing, the absorption peak of fullerene C60 occurs then shifts towards the long-wave region. The excitation energy decrease and the excitation wavelength increase correspondingly, and external electric ?eld makes fullerene C60 absorb energy from 1.01 to 2.31 eV in theory. The energy gap decreases drastically from 2.74 to 1.38 eV, which contributed to tune the energy gap of fullerene C60 by the effect of the electric ?eld in a wide range. It is possible to use electric ?eld to tune fullerene C60 into new energy storage material.
关键词： External electric ?eld,Excited state,Cluster,IR spectrum,Fullerene C60
更新于2025-09-23 15:23:52
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Significant Enhancement of Hole Transport Ability in Conjugated Polymer/Fullerene Bulk Heterojunction Microspheres
摘要： Bulk heterojunction (BHJ) strategy requires morphology of wide area donor-acceptor interfaces with high charge carrier mobilities through the bicontinuous charge transporting layers. Here, we report formation of well-defined bulk heterojunction (BHJ) microspheres from regiorandom poly(hexylthiophene) (rra-PHT)/phenyl-C61-butyric acid methyl ester (PCBM) mixture by a vapor diffusion method. By electrochemical oxidation, the BHJ microsphere exhibits enhanced generation of PHT cation species due to increased hole-transport property in comparison with a solution-cast film derived from rra-PHT/PCBM mixture without microsphere morphology. Photoconductivity and electrochemical stability of the microsphere are comparable or even higher than a cast film of irregular aggregates of regioregular P3HT.
关键词： polythiophene,bulk heterojunction,microspheres,electrochemistry,fullerene
更新于2025-09-23 15:22:29
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Charge transfer processes and carrier dynamics at the pentacene - C60 interface
摘要： Heterostructures of pentacene (PEN) and Buckminsterfullerene (C60) are frequently attracting scientific interest as a well-defined small-molecule model-system for the study of internal interfaces between two organic semiconductors. They are prototypical representatives forming a donor-acceptor combination for studies of fundamental optoelectronic processes in organic photovoltaics. Despite their importance in exciton dissociation, the energetics of their interfacial charge-transfer (CT) states and their microscopic excitation dynamics are not yet clarified and still being discussed. Here, we present steady-state and time-resolved photoluminescence measurements on stacked heterostructures between these two materials. All experiments are performed in the visible and near-infrared spectral regions as CT states are expected at energies below the fundamental electronic transitions of the respective bulk materials. A characteristic, interface specific emission at around 1.13-1.17 eV is found, which we attribute to an interfacial CT state. Its excitation-energy dependence reveals the intricate relaxation dynamics of excitons formed in both constituent materials. Moreover, the analysis of the dynamics of the C60 excitons shows that the lifetime of this state is reduced in the presence of an interface with PEN. This quenching is attributed to a long-range interaction, i.e., the relaxation of excitations into the interfacial CT state.
关键词： organic heterostructures,charge-transfer exciton,light harvesting,donor-acceptor pair,Organic thin films,pentacene,fullerene
更新于2025-09-23 15:22:29