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Acceptor Material (acceptor + material)

Distribution by Scientific Domains

Polymers and Materials Science	88%

Selected Abstracts

Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer Organic Solar Cell

ADVANCED FUNCTIONAL MATERIALS, Issue 21 2009
Hans Gommans
Abstract The complex refractive index of fluorinated subphthalocyanines (SubPcs) deposited by vacuum sublimation is determined by spectral ellipsometry. Their performance as acceptor material is characterized in a range of donor/acceptor heterojunctions in organic photovoltaic cells (OPVCs) by current,voltage measurements under 1,sun AM 1.5D simulated solar illumination and spectral response. Both electron and hole transfer between donor and acceptor materials is demonstrated. Power conversion efficiencies of 0.96% are found with an open-circuit bias of 940,mV. Hence, it is shown that fluorinated SubPcs can be considered as an acceptor material in OPVCs with an absorption in the visible comparable to that of well-known metallophthalocyanines. [source]

High-Yield Synthesis and Electrochemical and Photovoltaic Properties of Indene-C70 Bisadduct

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
Youjun He
Abstract [6, 6]-Phenyl-C61 -butyric acid methyl ester (PC60BM) is the widely used acceptor material in polymer solar cells (PSCs). Nevertheless, the low LUMO energy level and weak absorption in visible region are its two weak points. For enhancing the solar light harvest, the soluble C70 derivative PC70BM has been used as acceptor instead of PC60BM in high efficiency PSCs in recent years. But, the LUMO level of PC70BM is the same as that of PC60BM, which is too low for the PSCs based on the polymer donors with higher HOMO level, such as poly (3-hexylthiophene) (P3HT). Here, a new soluble C70 derivative, indene-C70 bisadduct (IC70BA), is synthesized with high yield of 58% by a one-pot reaction of indene and C70 at 180 °C for 72 h. The electrochemical properties and electronic energy levels of the fullerene derivatives are measured by cyclic voltammetry. The LUMO energy level of IC70BA is 0.19 eV higher than that of PC70BM. The PSC based on P3HT with IC70BA as acceptor shows a higher Voc of 0.84 V and higher power conversion efficiency (PCE) of 5.64%, while the PSC based on P3HT/PC60BM and P3HT/PC70BM displays Voc of 0.59 V and 0.58 V, and PCE of 3.55% and 3.96%, respectively, under the illumination of AM1.5G, 100 mW cm,2. The results indicate that IC70BA is an excellent acceptor for the P3HT-based PSCs and could be a promising new acceptor instead of PC70BM for the high performance PSCs based on narrow bandgap conjugated polymer donor. [source]

Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer Organic Solar Cell

Tuning Conversion Efficiency in Metallo Endohedral Fullerene-Based Organic Photovoltaic Devices

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009
Russel B. Ross
Abstract Here the influence that 1-(3-hexoxycarbonyl)propyl-1-phenyl-[6,6]-Lu3N@C81, Lu3N@C80,PCBH, a novel acceptor material, has on active layer morphology and the performance of organic photovoltaic (OPV) devices using this material is reported. Polymer/fullerene blend films with poly(3-hexylthiophene), P3HT, donor material and Lu3N@C80,PCBH acceptor material are studied using absorption spectroscopy, grazing incident X-ray diffraction and photocurrent spectra of photovoltaic devices. Due to a smaller molecular orbital offset the OPV devices built with Lu3N@C80,PCBH display increased open circuit voltage over empty cage fullerene acceptors. The photovoltaic performance of these metallo endohedral fullerene blend films is found to be highly impacted by the fullerene loading. The results indicate that the optimized blend ratio in a P3HT matrix differs from a molecular equivalent of an optimized P3HT/[6,6]-phenyl-C61 -butyric methyl ester, C60,PCBM, active layer, and this is related to the physical differences of the C80 fullerene. The influence that active layer annealing has on the OPV performance is further evaluated. Through properly matching the film processing and the donor/acceptor ratio, devices with power conversion efficiency greater than 4% are demonstrated. [source]

Polymer Photovoltaic Cells Based on Solution-Processable Graphene and P3HT

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Qian Liu
Abstract A soluble graphene, which has a one-atom thickness and a two-dimensional structure, is blended with poly(3-hexylthiophene) (P3HT) and used as the active layer in bulk heterojunction (BHJ) polymer photovoltaic cells. Adding graphene to the P3HT induces a great quenching of the photoluminescence of the P3HT, indicating a strong electron/energy transfer from the P3HT to the graphene. In the photovoltaic devices with an ITO/PEDOT:PSS/P3HT:graphene/LiF/Al structure, the device efficiency increases first and then decreases with the increase in the graphene content. The device containing only 10,wt % of graphene shows the best performance with a power conversion efficiency of 1.1%, an open-circuit voltage of 0.72,V, a short-circuit current density of 4.0,mA cm,2, and a fill factor of 0.38 under simulated AM1.5G conditions at 100,mW cm,2 after an annealing treatment at 160,°C for 10,min. The annealing treatment at the appropriate temperature (160,°C, for example) greatly improves the device performance; however, an annealing at overgenerous conditions such as at 210,°C results in a decrease in the device efficiency (0.57%). The morphology investigation shows that better performance can be obtained with a moderate content of graphene, which keeps good dispersion and interconnection. The functionalized graphene, which is cheap, easily prepared, stable, and inert against the ambient conditions, is expected to be a competitive candidate for the acceptor material in organic photovoltaic applications. [source]

Photo-induced Charge Transfer and Relaxation of Persistent Charge Carriers in Polymer/Nanocrystal Composites for Applications in Hybrid Solar Cells

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
Marc Daniel Heinemann
Abstract The photo-induced charge transfer and the dynamics of persistent charge carriers in blends of semiconducting polymers and nanocrystals are investigated. Regioregular poly(3-hexylthiophene) (P3HT) is used as the electron donor material, while the acceptor moiety is established by CdSe nanocrystals (nc-CdSe) prepared via colloidal synthesis. As a reference system, organic blends of P3HT and [6,6]-phenyl C61 -butyric acid methyl ester (PCBM) are studied as well. The light-induced charge transfer between P3HT and the acceptor materials is studied by photoluminescence (PL), photo-induced absorption (PIA) and light-induced electron spin resonance spectroscopy (LESR). Compared to neat P3HT samples, both systems show an intensified formation of polarons in the polymer upon photo-excitation, pointing out successful separation of photogenerated charge carriers. Additionally, relaxation of the persistent charge carriers is investigated, and significant differences are found between the hybrid composite and the purely organic system. While relaxation, reflected in the transient signal decay of the polaron signal, is fast in the organic system, the hybrid blends exhibit long-term persistence. The appearance of a second, slow recombination channel indicates the existence of deep trap states in the hybrid system, which leads to the capture of a large fraction of charge carriers. A change of polymer conformation due to the presence of nc-CdSe is revealed by low temperature LESR measurements and microwave saturation techniques. The impact of the different recombination behavior on the photovoltaic efficiency of both systems is discussed. [source]

Perfluorinated Subphthalocyanine as a New Acceptor Material in a Small-Molecule Bilayer Organic Solar Cell

Conjugated-Polymer Blends for Optoelectronics

ADVANCED MATERIALS, Issue 38-39 2009
Christopher R. McNeill
Abstract Solution-processed polymer optoelectronic devices such as light-emitting diodes and solar cells have many advantages for large-area manufacture, and show increasing levels of performance. Here, we review recent progress in using blends of two conjugated polymers for optoelectronic devices. The blending of two or more polymers allows tuning of device performance, and for photovoltaics presents an attractive way to combine donor and acceptor materials with a morphology controlled by polymer phase separation. We discuss recent advances in imaging the microstructure of conjugated polymer blends, and we demonstrate how the blend structure leads to performance advantages in both LEDs and photovoltaic devices. [source]

Synthesis and Electrochemical Studies of Bingel,Hirsch Derivatives of M3N@Ih -C80 (M=Sc, Lu)

CHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2010
Julio
Abstract Bingel,Hirsch derivatives of the trimetallic nitride template endohedral metallofullerenes (TNT-EMFs) Sc3N@Ih -C80 and Lu3N@Ih -C80 were prepared by reacting these compounds with 2-bromodiethyl malonate, 2-bromo-1,3-dipyrrolidin-1-ylpropane-1,3-dionate bromide, and 9-bromo fluorene. The mono-adducts were isolated and their 1H,NMR spectra showed that the addition occurred with high regioselectivity at the [6,6] bonds of the Ih -C80 fullerene cage. Electrochemical analysis showed that the reductive electrochemistry behavior of these derivatives is irreversible at a scan rate of 100,mV,s,1, which is comparable to the behavior of the pristine fullerene species. The first reduction potential of each derivative is either cathodically or anodically shifted by a different value, depending on the attached addend. Bis-adducts containing EtOOC-C-COOEt and HC-COOEt addends were isolated by HPLC and in the case of Sc3N@Ih -C80 the first reduction potential exhibits a larger shift towards negative potentials when compared to the mono-adduct. This observation is important for designing acceptor materials for the construction of bulk heterojunction (BHJ) organic solar cells, since the polyfunctionalization not only increases the solubility of the fullerene species but also offers a promising approach for bringing the LUMO energy levels closer for the donor and the acceptor materials. [source]