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Polymer Solar Cells (polymer + solar_cell)
Selected AbstractsOrigin of Radiation-Induced Degradation in Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Ankit Kumar Abstract Polymer solar cells have been shown to degrade under X-rays. Here, in situ polymer photovoltaic performance and recombination lifetimes are measured and it is found that charge accumulation is the primary reason for degradation of solar cells. This is affected by the mixing ratio of donor and acceptor in the bulk heterojunction. Both a quantitative understanding and the physical model of the degradation mechanism are presented. Understanding of the degradation mechanism is extended in polymer donor,acceptor bulk heterojunction systems to propose a material combination for making radiation hard diodes that can find important application in fields ranging from memory arrays to organic X-ray detectors for medical imaging. [source] Annealing-Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting ProcessADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Jae Woong Jung Abstract Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller-painted film , composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) , has a smoother surface than a spin-coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller-painted active layer contribute to enhanced and balanced charge-carrier mobility. Consequently, the roller-painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing-free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi-1,8-thiol. Since the addition of octanedi-1,8-thiol induces phase separation between P3HT and PCBM and the roller-painting process induces crystallization of P3HT and PCBM, a PCE of roller-painted PSCs of up to 3.8% is achieved without post-annealing. A PCE of over 2.7% can also be achieved with 5,cm2 of active area without post-annealing. [source] Abrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Minjung Shin Abstract The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology,including the size and population of P3HT crystallites,abruptly changes at 140,°C between 5 and 30,min and is then stable up to 120,min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5,min annealing at 140,°C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high. [source] Three-Dimensional Bulk Heterojunction Morphology for Achieving High Internal Quantum Efficiency in Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Jang Jo Abstract Here, an investigation of three-dimensional (3D) morphologies for bulk heterojunction (BHJ) films based on regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM) is reported. Based on the results, it is demonstrated that optimized post-treatment, such as solvent annealing, forces the PCBM molecules to migrate or diffuse toward the top surface of the BHJ composite films, which induces a new vertical component distribution favorable for enhancing the internal quantum efficiency (,IQE) of the devices. To investigate the 3D BHJ morphology, novel time-of-flight secondary-ion mass spectroscopy studies are employed along with conventional methods, such as UV-vis absorption, X-ray diffraction, and high-resolution transmission electron microscopy studies. The ,IQE of the devices are also compared after solvent annealing for different times, which clearly shows the effect of the vertical component distribution on the performance of BHJ polymer solar cells. In addition, the fabrication of high-performance P3HT:PCBM solar cells using the optimized solvent-annealing method is reported, and these cells show a mean power-conversion efficiency of 4.12% under AM 1.5G illumination conditions at an intensity of 100,mW cm,2. [source] Effects of Solvent Mixtures on the Nanoscale Phase Separation in Polymer Solar Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2008Yan Yao Abstract The mixed solvent approach has been demonstrated as a promising method to modify nanomorphology in polymer solar cells. This work aims to understand the unique role of the additive in the mixture solvent and how the optimized nanoscale phase separation develops laterally and vertically during the non-equilibrium spin-coating process. We found the donor/acceptor components in the active layer can phase separate into an optimum morphology with the additive. Supported by AFM, TEM and XPS results, we proposed a model and identified relevant parameters for the additive such as solubility and vapor pressures. Other additives are discovered to show the ability to improve polymer solar cell performance as well. [source] Polymer Solar Cells Based on a Low-Bandgap Fluorene Copolymer and a Fullerene Derivative with Photocurrent Extended to 850,nm,ADVANCED FUNCTIONAL MATERIALS, Issue 5 2005F. Zhang Abstract Polymer solar cells have been fabricated from a recently synthesized low band-gap alternating polyfluorene copolymer, APFO-Green2, combined with [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM) from organic solutions. External quantum efficiencies (EQEs) of the solar cells show an onset at 850,nm and a peak of >,10,% located at 650,nm, which corresponds to the extended absorption spectrum of the polymer. Photocurrent of 3.0,mA,cm,2, photovoltage of 0.78,V, and power conversion efficiency of 0.9,% have been achieved in solar cells based on this new low-bandgap polymer under the illumination of air mass,1.5 (AM,1.5) (1000,W,m,2) from a solar simulator. [source] A Facile Route to Polymer Solar Cells with Optimum Morphology Readily Applicable to a Roll-to-Roll Process without Sacrificing High Device PerformancesADVANCED MATERIALS, Issue 35 2010Hui Joon Park A new fabrication method for polymer solar cells that can produce optimized vertical distribution of components is reported. The favorable donor,acceptor morphology showing a well-organized photo-induced charge transporting pathway with fine nanodomains and high crystallinity is achieved. This process is also readily scalable to a large-area and high-speed roll-to-roll process without sacrificing high device performances, even without a PEDOT:PSS layer. [source] For the Bright Future,Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%ADVANCED MATERIALS, Issue 20 2010Yongye Liang The photovoltaic performance of polymer bulk heterojunction solar cells is studied systematically. Using a new benzodithiophene polymer (PTB7) and PC71BM (see figure) a power conversion efficiency of 7.4% has been achieved in PTB7/PC71BM-blend film, indicating a great potential and bright future for polymer solar cells (FF,=,fill factor, PCE,;=,power-conversion efficiency). [source] Efficient Polymer Solar Cells with Thin Active Layers Based on Alternating Polyfluorene Copolymer/Fullerene Bulk HeterojunctionsADVANCED MATERIALS, Issue 42 2009Mei-Hsin Chen Efficient (4.5% power conversion efficiency) polymer solar cells based on an alternating polyfluorene copolymer are demonstrated. The highest internal quantum efficiency obtained was 87%. The semi-transparent active layer (only 47,nm thick) shows the uniqueness of polymer solar cells and their unconventional applications, such as translucent solar windows for buildings and automobiles. [source] Recent Progress in Polymer Solar Cells: Manipulation of Polymer:Fullerene Morphology and the Formation of Efficient Inverted Polymer Solar CellsADVANCED MATERIALS, Issue 14-15 2009Li-Min Chen Abstract Polymer morphology has proven to be extremely important in determining the optoelectronic properties in polymer-based devices. The understanding and manipulation of polymer morphology has been the focus of electronic and optoelectronic polymer-device research. In this article, recent advances in the understanding and controlling of polymer morphology are reviewed with respect to the solvent selection and various annealing processes. We also review the mixed-solvent effects on the dynamics of film evolution in selected polymer-blend systems, which facilitate the formation of optimal percolation paths and therefore provide a simple approach to improve photovoltaic performance. Recently, the occurrence of vertical phase separation has been found in some polymer:fullerene bulk heterojunctions.1,3 The origin and applications of this inhomogeneous distribution of the polymer donor and fullerene acceptor are addressed. The current status and device physics of the inverted structure solar cells is also reviewed, including the advantage of utilizing the spontaneous vertical phase separation, which provides a promising alternative to the conventional structure for obtaining higher device performance. [source] Efficient Polymer Solar Cells Fabricated by Simple Brush Painting,ADVANCED MATERIALS, Issue 24 2007S.-S. Kim We demonstrate a brushing technique as a promising method for the mass production of efficient and flexible solar cells even on a non-flat surface such as roofing tiles. Higher device efficiency could be obtained compared to the spin-coated devices, resulting from the improved organization of polymer chains and domains induced by more effective application of shear stress to the polymer chains during the brushing process. [source] High-Performance Polymer Solar Cells of an Alternating Polyfluorene Copolymer and a Fullerene Derivative,ADVANCED MATERIALS, Issue 12 2003M. Svensson Solar cells prepared using the alternating copolymer shown in the Figure blended with a C60 derivative (PCBM) are demonstrated to have a high performance, with a power conversion efficiency of 2.2,% under simulated solar light. The molecular weight of the polymer is low due to limited solubility, and films of the polymer exhibit red-shifted absorption. [source] A New Poly(2,7-Dibenzosilole) Derivative in Polymer Solar CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 2007Pierre-Luc T. Boudreault Abstract A new soluble conjugated copolymer based on 2,7-dibenzosilole and 4,7-dithien-2-yl-2,1,3-benzothiadiazole units has been synthesized (PBSDTBT). Bulk heterojunction solar cell devices are fabricated using this material as the donor and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) as the acceptor. The power conversion efficiency is 1.6% under AM1.5 illumination. This material also shows a good VOC (0.97 V). The results are quite promising considering the relatively large bandgap (1.9 eV) of this polymer. [source] Linking Polythiophene Chains Through Conjugated Bridges: A Way to Improve Charge Transport in Polymer Solar CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 10 2006Erjun Zhou Abstract Summary: A series of cross-linked polythiophene derivatives (P1,4) are synthesized by adding different ratio (0, 2, 5, and 10%) of conjugated cross-linker via a Stille coupling reaction. From P1,4, with the increase of the content of the conjugated bridges, the UV-visible absorption peaks of the polymers were shifted towards blue and their electrochemical bandgap increased. The hole mobilities of P1,4 as determined from the SCLC model are 5.23,×,10,6, 1.28,×,10,4, 7.01,×,10,3, and 2.34,×,10,5 cm2,·,V,1,·,s,1, respectively. The PCEs of the polymer solar cells based on P1,4 are 0.37, 1.05, 1.26, and 0.78%, respectively. The improvement of PCE of the devices based on P2,4 compared with that of P1 may be due to the increase of hole mobility. Molecular structure of the polythiophene derivatives (P1,4). [source] A Polybenzo[1,2- b:4,5- b,]dithiophene Derivative with Deep HOMO Level and Its Application in High-Performance Polymer Solar Cells,ANGEWANDTE CHEMIE, Issue 8 2010Lijun Huo Dr. Sonnenanbeter: Das neue Polymer PBDTTBT erreicht Leistungsumwandlungseffizienzen bis 5.66,%. Die hohe Leerlaufspannung (0.92,V) ergibt sich aus der niedrigen HOMO-Energie des Polymers und hohen internen (IQE) wie externen Quanteneffizienzen (EQE) in einem großen Spektralbereich. PBDTTBT ist ein vielversprechendes Donormaterial für Polymersolarzellen. [source] Synthesis and properties of new dialkoxyphenylene quinoxaline-based donor-acceptor conjugated polymers and their applications on thin film transistors and solar cellsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2009Mei-Hsiu Lai Abstract Synthesis, properties, and optoelectronic device applications of four new bis-[4-(2-ethyl-hexyloxy)-phenyl]quinoxaline(Qx(EHP))-based donor-acceptor conjugated copolymers are reported, in which the donors are thiophene(T), dithiophene(DT), dioctylfluorene(FO), and didecyloxyphenylene(OC10). The optical band gaps (Eg) of PThQx(EHP), PDTQ(EHP), POC10DTQ(EHP), and PFODTQ(EHP) estimated from the onset absorption are 1.57, 1.65, 1.77, and 1.92 eV, respectively. The smallest Eg of PThQx(EHP) among the four copolymers is attributed to the balanced donor/acceptor ratio and backbone coplanarity, leading to a strong intramolecular charge transfer. The hole mobilities obtained from the thin film transistor (TFT) devices of PThQx(EHP), PDTQ(EHP), POC10DTQ(EHP), and PFODTQ(EHP) are 2.52 × 10,4, 4.50 × 10,3, 4.72 × 10,5, and 9.31 × 10,4 cm2 V,1 s,1, respectively, with the on-off ratios of 2.00 × 104, 1.89 × 103, 4.07 × 103, and 2.30 × 104. Polymer solar cell based on the polymer blends of PFODTQ(EHP), PThQx(EHP), POC10DTQ(EHP), and PDTQ(EHP) with [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) under illumination of AM1.5 (100 mW cm,2) solar simulator exhibit power conversion efficiencies of 1.75, 0.92, 0.79, and 0.43%, respectively. The donor/acceptor strength, molecular weight, miscibility, and energy level lead to the difference on the TFT or solar cell characteristics. The present study suggests that the prepared bis[4-(2-ethyl-hexyloxy)-phenyl]quinoxaline donor-acceptor conjugated copolymers would have promising applications on electronic device applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 973,985, 2009 [source] Origin of Radiation-Induced Degradation in Polymer Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010Ankit Kumar Abstract Polymer solar cells have been shown to degrade under X-rays. Here, in situ polymer photovoltaic performance and recombination lifetimes are measured and it is found that charge accumulation is the primary reason for degradation of solar cells. This is affected by the mixing ratio of donor and acceptor in the bulk heterojunction. Both a quantitative understanding and the physical model of the degradation mechanism are presented. Understanding of the degradation mechanism is extended in polymer donor,acceptor bulk heterojunction systems to propose a material combination for making radiation hard diodes that can find important application in fields ranging from memory arrays to organic X-ray detectors for medical imaging. [source] Annealing-Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting ProcessADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Jae Woong Jung Abstract Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller-painted film , composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) , has a smoother surface than a spin-coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller-painted active layer contribute to enhanced and balanced charge-carrier mobility. Consequently, the roller-painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing-free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi-1,8-thiol. Since the addition of octanedi-1,8-thiol induces phase separation between P3HT and PCBM and the roller-painting process induces crystallization of P3HT and PCBM, a PCE of roller-painted PSCs of up to 3.8% is achieved without post-annealing. A PCE of over 2.7% can also be achieved with 5,cm2 of active area without post-annealing. [source] Doping of the Metal Oxide Nanostructure and its Influence in Organic ElectronicsADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Mi-Hyae Park Abstract Synthesizing metal oxides through the sol,gel process provides a convenient way for forming a nanostructured layer in wide band gap semiconductors. In this paper, a unique method of introducing dopants into the metal oxide semiconductor is presented. The doped TiO2 is prepared by adding a Cs2CO3 solution to a nanocrystalline TiO2 solution that is synthesized via a non-hydrolytic sol,gel process. The properties of the TiO2:Cs layer are investigated and the results show stable nanostructure morphology. In addition to providing morphological stability, Cs in TiO2 also gives rise to a more desirable work function for charge transport in organic electronics. Polymer solar cells based on the poly(3-hexylthiophene) (P3HT): methanofullerene (PC70BM) system with the addition of a TiO2:Cs interfacial layer exhibit excellent characteristics with a power conversion efficiency of up to 4.2%. The improved device performance is attributed to an improved polymer/metal contact, more efficient electron extraction, and better hole blocking properties. The effectiveness of this unique functionality also extends to polymer light emitting devices, where a lower driving voltage, improved efficiency, and extended lifetime are demonstrated. [source] Polymer Solar Cells Based on a Low-Bandgap Fluorene Copolymer and a Fullerene Derivative with Photocurrent Extended to 850,nm,ADVANCED FUNCTIONAL MATERIALS, Issue 5 2005F. Zhang Abstract Polymer solar cells have been fabricated from a recently synthesized low band-gap alternating polyfluorene copolymer, APFO-Green2, combined with [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM) from organic solutions. External quantum efficiencies (EQEs) of the solar cells show an onset at 850,nm and a peak of >,10,% located at 650,nm, which corresponds to the extended absorption spectrum of the polymer. Photocurrent of 3.0,mA,cm,2, photovoltage of 0.78,V, and power conversion efficiency of 0.9,% have been achieved in solar cells based on this new low-bandgap polymer under the illumination of air mass,1.5 (AM,1.5) (1000,W,m,2) from a solar simulator. [source] Soluble dithienothiophene polymers: Effect of link patternJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2009Shiming Zhang Abstract Soluble conjugated polymers based on 3,5-didecanyldithieno[3,2- b:2,,3,- d]thiophene,single-bond (1), double-bond (2), and triple-bond linked (3),were synthesized by palladium(0)-catalyzed Stille coupling reaction and oxidation polymerization. The thermal, absorption, emission, and electrochemical properties of these polymers were examined; the effect of the link pattern was studied. All polymers exhibit decomposition temperatures over 295 °C and glass-transition temperatures in the range of 137,202 °C. The absorption spectra of 1, 2, and 3 in thin films exhibit absorption maxima at 381, 584, and 444 nm, respectively. Polymer 1 exhibits intense green emission located at 510 nm in film, whereas polymers 2 and 3 are nonemissive both in solution and in film due to H-aggregate. Cyclic voltammograms of polymers 1, 2, and 3 display irreversible oxidation waves with onset oxidation potentials at 1.73, 0.78, and 1.03 V versus Ag+/Ag, respectively. Theory calculation on model compounds suggests that the dihedral angle decreases in the order of 1 > 3 > 2. On reducing the dihedral angle, the polymer exhibits a longer absorption maximum, a smaller bandgap, a less oxidizing potential and fluorescence quench, due to more coplanar and more ,-electron delocalized backbone structure. Polymer solar cells were fabricated based on the blend of polymer 2 and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM). The power conversion efficiency of 0.45% was achieved under AM 1.5, 100 mW cm,2 using polymer 2:PCBM (1:2, w/w) as active layer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2843,2852, 2009 [source] Effect of side-chain end groups on the optical, electrochemical, and photovoltaic properties of side-chain conjugated polythiophenesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2006Erjun Zhou Abstract Three new side-chain conjugated polythiophene derivatives, poly{3-[2-(3-methoxy-4-octyloxy-phenyl)-vinyl]-thiophene} (P3MOPVT), poly{3-[2-(3,5-dimethoxy-4-octyloxy-phenyl)-vinyl]-thiophene} (P3DMOPVT), and poly{3-[2-(3,4-dioctyloxy-phenyl)-vinyl]-thiophene} (P3DOPVT), were synthesized by Wittig-Hornor reaction and GRIM method and compared with poly{3-[2-(4-octyloxy-phenyl)-vinyl]-thiophene} (P3OPVT) for investigating the effect of the end groups of the conjugated side-chain on the properties of the polymers. Owing to the electron-donating ability of methoxy groups, the visible absorption peaks of P3MOPVT and P3DMOPVT solutions and films become stronger and red-shifted compared with P3OPVT. The electrochemical bandgaps of the four polymers are 2.15 eV for P3OPVT, 1.99 eV for P3MOPVT, 1.85 eV for P3DMOPVT, and 2.36 eV for P3DOPVT, respectively, which indicate that the electron-donating ability of the methoxy end group on the conjugated side chain of P3MOPVT and P3DMOPVT and the large steric hindrance of the two octyloxy end groups on the conjugated side chain of P3DOPVT have obvious influence on the electrochemical properties of the side-chain conjugated polythiophenes. Polymer solar cells were fabricated with a structure of ITO/PEDOT:PSS/Polymer:PCBM/LiF/Al. The best device, based on P3DMOPVT, shows a power conversion efficiency of 1.63% under the illumination of AM1.5, 80 mW/cm2. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4916,4922, 2006 [source] Stable Inverted Polymer/Fullerene Solar Cells Using a Cationic Polythiophene Modified PEDOT:PSS Cathodic InterfaceADVANCED FUNCTIONAL MATERIALS, Issue 15 2010David A. Rider Abstract A cationic and water-soluble polythiophene [poly[3-(6-pyridiniumylhexyl)thiophene bromide] (P3PHT+Br,)] is synthesized and used in combination with anionic poly(3,4-ethylenedioxythiophene):poly(p -styrenesulfonate) (PEDOT:PSS), to produce hybrid coatings on indium tin oxide (ITO). Two coating strategies are established: i) electrostatic layer-by-layer assembly with colloidal suspensions of (PEDOT:PSS),, and ii) modification of an electrochemically prepared (PEDOT:PSS), film on ITO. The coatings are found to modify the work function of ITO such that it could act as a cathode in inverted 2,5-diyl-poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61 -butyric acid methyl ester (PCBM) polymer photovoltaic cells. The interfacial modifier created from the layer-by-layer assembly route is used to produce efficient inverted organic photovoltaic devices (power conversion efficiency ,2%) with significant long-term stability in excess of 500,h. [source] Recombination-Limited Photocurrents in Low Bandgap Polymer/Fullerene Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Martijn Lenes Abstract The charge transport and photogeneration in solar cells based on the low bandgap-conjugated polymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H -cyclopenta[2,1-b; 3,4-b,]dithiophene)- alt -4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and fullerenes is studied. The efficiency of the solar cells is limited by a relatively low fill factor, which contradicts the observed good and balanced charge transport in these blends. Intensity dependent measurements display a recombination limited photocurrent, characterized by a square root dependence on effective applied voltage, a linear dependence on light intensity and a constant saturation voltage. Numerical simulations show that the origin of the recombination limited photocurrent stems from the short lifetime of the bound electron-hole pairs at the donor/acceptor interface. [source] The Effect of Polymer Optoelectronic Properties on the Performance of Multilayer Hybrid Polymer/TiO2 Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 4 2005P. Ravirajan Abstract We report a study of the effects of polymer optoelectronic properties on the performance of photovoltaic devices consisting of nanocrystalline TiO2 and a conjugated polymer. Three different poly(2-methoxy-5-(2,-ethylhexoxy)-1,4-phenylenevinylene) (MEH-PPV)-based polymers and a fluorene,bithiophene copolymer are compared. We use photoluminescence quenching, time-of-flight mobility measurements, and optical spectroscopy to characterize the exciton-transport, charge-transport, and light-harvesting properties, respectively, of the polymers, and correlate these material properties with photovoltaic-device performance. We find that photocurrent is primarily limited by the photogeneration rate and by the quality of the interfaces, rather than by hole transport in the polymer. We have also studied the photovoltaic performance of these TiO2/polymer devices as a function of the fabrication route and device design. Including a dip-coating step before spin-coating the polymer leads to excellent polymer penetration into highly structured TiO2 networks, as was confirmed through transient optical measurements of the photoinduced charge-transfer yield and recombination kinetics. Device performance is further improved for all material combinations studied, by introducing a layer of poly(ethylene dioxythiophene) (PEDOT) doped with poly(styrene sulfonic acid) (PSS) under the top contact. Optimized devices incorporating the additional dip-coated and PEDOT:PSS layers produced a short-circuit current density of about 1,mA,cm,2, a fill factor of 0.50, and an open-circuit voltage of 0.86,V under simulated AM,1.5 illumination (100,mW,cm,2, 1,sun). The corresponding power conversion efficiency under 1,sun was ,,0.4,%. [source] Device Performance of APFO-3/PCBM Solar Cells with Controlled MorphologyADVANCED MATERIALS, Issue 43 2009Cecilia M. Björström Svanström Polymer/fullerene solar cells with three different device structures: A) diffuse bilayer, B) spontaneously formed multilayer, and C) vertically homogenous thin films, are fabricated. The photocurrent/voltage performance is compared and it is found that the self-stratified structure (B) yields the highest energy conversion efficiency. [source] Bulk Heterojunction Solar Cells: The Role of Processing in the Fabrication and Optimization of Plastic Solar Cells (Adv. Mater.ADVANCED MATERIALS, Issue 14-15 200915/2009) Alan Heeger and co-workers report on page 1521 on the role of processing methodology in the fabrication and optimization of bulk heterojunction (BHJ) ,plastic' solar cells. Several techniques that have recently been used to optimize the BHJ nanomorphology are discussed and compared and some insights are given into the mechanisms behind these various techniques. The cover image depicts a multilayer solar cell ribbon along with the polymer, fullerene, and solvent additive, which were used to fabricate a low bandgap polymer solar cell with greater than 5% power conversion efficiency. [source] Nanowire,quantum-dot,polymer solar cellPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2008A. Nadarajah Abstract We report first results on a new solar cell structure which incorporates n-type ZnO nanowires, an undoped CdSe layer, obtained from quantum dot precursors, and a p-type polymer layer as the main components. In the fabrication process the quantum dot layer is converted to a conformal ,30 nm thick polycrystalline film. The fabrication of the cell occurs in lab air at temperatures below 100 °C. Several intermittent annealing steps raise the energy conversion efficiency to approximately 1%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High-Yield Synthesis and Electrochemical and Photovoltaic Properties of Indene-C70 BisadductADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Youjun 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] Annealing-Free High Efficiency and Large Area Polymer Solar Cells Fabricated by a Roller Painting ProcessADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Jae Woong Jung Abstract Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller-painted film , composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) , has a smoother surface than a spin-coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller-painted active layer contribute to enhanced and balanced charge-carrier mobility. Consequently, the roller-painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing-free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi-1,8-thiol. Since the addition of octanedi-1,8-thiol induces phase separation between P3HT and PCBM and the roller-painting process induces crystallization of P3HT and PCBM, a PCE of roller-painted PSCs of up to 3.8% is achieved without post-annealing. A PCE of over 2.7% can also be achieved with 5,cm2 of active area without post-annealing. [source] | |||||||||||||||||||||||||