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Solar Cell Performance (solar + cell_performance)

Distribution by Scientific Domains

Physics and Astronomy	41%
Polymers and Materials Science	35%

Selected Abstracts

Control of Solid-State Dye-Sensitized Solar Cell Performance by Block-Copolymer-Directed TiO2 Synthesis

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010
Pablo Docampo
Abstract Hybrid dye-sensitized solar cells are typically composed of mesoporous titania (TiO2), light-harvesting dyes, and organic molecular hole-transporters. Correctly matching the electronic properties of the materials is critical to ensure efficient device operation. In this study, TiO2 is synthesized in a well-defined morphological confinement that arises from the self-assembly of a diblock copolymer,poly(isoprene- b -ethylene oxide) (PI- b -PEO). The crystallization environment, tuned by the inorganic (TiO2 mass) to organic (polymer) ratio, is shown to be a decisive factor in determining the distribution of sub-bandgap electronic states and the associated electronic function in solid-state dye-sensitized solar cells. Interestingly, the tuning of the sub-bandgap states does not appear to strongly influence the charge transport and recombination in the devices. However, increasing the depth and breadth of the density of sub-bandgap states correlates well with an increase in photocurrent generation, suggesting that a high density of these sub-bandgap states is critical for efficient photo-induced electron transfer and charge separation. [source]

A CdSe Nanowire/Quantum Dot Hybrid Architecture for Improving Solar Cell Performance

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2010
Yanghai Yu
Abstract Incorporating colloidal CdSe quantum dots (QDs) into CdSe nanowire (NW)-based photoelectrochemical solar cells increases their incident-photon-to-carrier conversion efficiencies (IPCE) from 13% to 25% at 500,nm. While the effect could, in principle, stem from direct absorption and subsequent carrier generation by QDs, the overall IPCE increase occurs across the entire visible spectrum, even at wavelengths where the dots do not absorb light. This beneficial effect originates from an interplay between NWs and QDs where the latter fill voids between interconnected NWs, providing electrically accessible conduits, in turn, enabling better carrier transport to electrodes. The presence of QDs furthermore reduces the residual polarization anisotropy of random NW networks. Introducing QDs therefore addresses an important limiting constraint of NW photoelectrochemical solar cells. The effect appears to be general and may aid the future design and implementation of other NW-based photovoltaics. [source]

A Conjugated Polymer for Near Infrared Optoelectronic Applications,

ADVANCED MATERIALS, Issue 20 2007
E. Perzon
A new conjugated polymer, LBPP-1, with an unusually low band-gap (ca.,1.0,eV) is presented. Light absorption and photovoltaic response up to 1200,nm in composites with a fullerene is demonstrated. Solar cell performance is presented and the polymer's suitability for photodetection in the infrared region is discussed. [source]

General temperature dependence of solar cell performance and implications for device modelling

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2003
Martin A. Green
Solar cell performance generally decreases with increasing temperature, fundamentally owing to increased internal carrier recombination rates, caused by increased carrier concentrations. The temperature dependence of a general solar cell is investigated on the basis of internal device physics, producing general results for the temperature dependence of open-circuit voltage and short-circuit current, as well as recommendations for generic modelling. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Solution Processable Fluorenyl Hexa- peri -hexabenzocoronenes in Organic Field-Effect Transistors and Solar Cells

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
Wallace W. H. Wong
Abstract The organization of organic semiconductor molecules in the active layer of organic electronic devices has important consequences to overall device performance. This is due to the fact that molecular organization directly affects charge carrier mobility of the material. Organic field-effect transistor (OFET) performance is driven by high charge carrier mobility while bulk heterojunction (BHJ) solar cells require balanced hole and electron transport. By investigating the properties and device performance of three structural variations of the fluorenyl hexa- peri -hexabenzocoronene (FHBC) material, the importance of molecular organization to device performance was highlighted. It is clear from 1H NMR and 2D wide-angle X-ray scattering (2D WAXS) experiments that the sterically demanding 9,9-dioctylfluorene groups are preventing ,,, intermolecular contact in the hexakis-substituted FHBC 4. For bis-substituted FHBC compounds 5 and 6, ,,, intermolecular contact was observed in solution and hexagonal columnar ordering was observed in solid state. Furthermore, in atomic force microscopy (AFM) experiments, nanoscale phase separation was observed in thin films of FHBC and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blends. The differences in molecular and bulk structural features were found to correlate with OFET and BHJ solar cell performance. Poor OFET and BHJ solar cells devices were obtained for FHBC compound 4 while compounds 5 and 6 gave excellent devices. In particular, the field-effect mobility of FHBC 6, deposited by spin-casting, reached 2.8,×,10,3,cm2 V,1 s and a power conversion efficiency of 1.5% was recorded for the BHJ solar cell containing FHBC 6 and PC61BM. [source]

Charge Generation and Photovoltaic Operation of Solid-State Dye-Sensitized Solar Cells Incorporating a High Extinction Coefficient Indolene-Based Sensitizer

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Henry J. Snaith
Abstract An investigation of the function of an indolene-based organic dye, termed D149, incorporated in to solid-state dye-sensitized solar cells using 2,2,,7,7,-tetrakis(N,N -di- p -methoxypheny-amine)-9,9,-spirobifluorene (spiro-OMeTAD) as the hole transport material is reported. Solar cell performance characteristics are unprecedented under low light levels, with the solar cells delivering up to 70% incident photon-to-current efficiency (IPCE) and over 6% power conversion efficiency, as measured under simulated air mass (AM) 1.5 sun light at 1 and 10,mW cm,2. However, a considerable nonlinearity in the photocurrent as intensities approach "full sun" conditions is observed and the devices deliver up to 4.2% power conversion efficiency under simulated sun light of 100,mW cm,2. The influence of dye-loading upon solar cell operation is investigated and the thin films are probed via photoinduced absorption (PIA) spectroscopy, time-correlated single-photon counting (TCSPC), and photoluminescence quantum efficiency (PLQE) measurements in order to deduce the cause for the non ideal solar cell performance. The data suggest that electron transfer from the photoexcited sensitizer into the TiO2 is only between 10 to 50% efficient and that ionization of the photo excited dye via hole transfer directly to spiro-OMeTAD dominates the charge generation process. A persistent dye bleaching signal is also observed, and assigned to a remarkably high density of electrons "trapped" within the dye phase, equivalent to 1.8,×,1017,cm,3 under full sun illumination. it is believed that this localized space charge build-up upon the sensitizer is responsible for the non-linearity of photocurrent with intensity and nonoptimum solar cell performance under full sun conditions. [source]

Effects of Solvent Mixtures on the Nanoscale Phase Separation in Polymer Solar Cells,

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2008
Yan 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]

Electrochemical preparation of MoO3 buffer layer deposited onto the anode in organic solar cells

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2010
M. Gacitua
Abstract In this work the authors have studied the advantages of using electrochemically deposited molybdenum oxide as a buffer layer in an organic bilayer heterojunction solar cell arrangement. Furthermore, it has been probed that electrochemistry provides an alternative low cost, reproducible and less laborious method to prepare thin layered deposits. The precursor solution is composed by a concentrated molybdic acid solution in a sulphuric media in order to ensure the obtainment of low reduced molybdenum species. Therefore, by means of potentiostatic techniques, ITO/molybdenum oxide transparent anodes were tested for the photovoltaic device showing improved surface properties. XDR and AFM techniques were used to characterize the morphology of the deposits. The films with optimum thickness (5,nm) are amorphous. XPS analysis indicates that the best results in solar cell performance are in hand with a heterogeneous composition of the molybdenum oxide film presenting MoV and MoVI as predominant species. The MoO3 films deposited by cyclic voltammetry are not as homogeneous as those deposited by potentiostatic technique and only MoVI species are present. These differences may justify the different behaviour of the solar cells using these different buffer layers. Only buffer layers deposited by potentiostatic technique allow improving the cells performances in the same way than those achieved by evaporation. [source]

Effects of water vapor introduction during Cu(In1,xGax)Se2 deposition on thin film properties and solar cell performance

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006
S. Ishizuka
Abstract The effects of water vapor introduction during the growth of Cu(In1,xGax)Se2, specifically CuInSe2 (CISe), Cu(In,Ga)Se2 (CIGSe), and CuGaSe2 (CGSe) thin films were studied. We have developed thus far a novel technique to improve CIGSe (x , 0.5) cell performance by means of water vapor introduction during CIGSe deposition. In this study, we have examined the effectiveness of water vapor introduction for other x -compositions (CISe and CGSe). Variations in the electrical properties observed in CIGSe (x , 0.5), that is, increasing hole density and conductivity with water vapor introduction, were also observed in CISe and CGSe. Water vapor introduction affected solar cell performance as well; open circuit voltages, short circuit current densities, and efficiencies were improved. The improvements in cell performance are thought to be related to annihilation of donor defects arising from Se-vacancies by incorporation of oxygen from the water vapor. In addition to this, the sodium content in the CIGSe layers was found to depend on the partial pressure of water vapor during deposition. This result suggests that the improvement mechanism is also related with the so-called ,Na-effects'. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Microcrystalline silicon n-i-p solar cells prepared with microcrystalline silicon oxide (,c-SiOx:H) n-layer

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3-4 2010
Vladimir Smirnov
Abstract N-type hydrogenated microcrystalline silicon oxide (,c-SiOx:H) layers were used as window layers in n-side illuminated microcrystalline silicon n,i,p solar cells. Optical, electrical and structural properties of ,c-SiOx:H films were investigated by Photothermal Deflection Spectroscopy, conductivity and Raman scattering measurements. ,c-SiOx:H layers were prepared over a range of carbon dioxide (CO2) flow and film thickness, and the effects on the solar cell performance were investigated. By optimising the ,c-SiOx:H window layer properties, an improved short-circuit current density of 23.4 mA/cm2 is achieved, leading to an efficiency of 8.0% for 1,m thick absorber layer and Ag back contact. The correlation between cell performance and ,c-SiOx:H layer properties is discussed. The results are compared to the performance of solar cells prepared with alternative optimised window layers. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Admittance spectroscopy defect density of electrodeposited CuIn(S,Se)2 and its correlation with solar cells performances

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2008
A. Darga
Abstract Electrodeposited CuIn(S,Se)2 based solar cells with varying CdS buffer layer thicknesses were studied by admittance spectroscopy. An electrically active defect was identified. Its density of states which varies with CdS layer deposition process was found to be correlated with solar cell performance. This defect seems to be CdS/CuIn(S,Se)2 interface defect or to be located within the grain boundaries of the absorber layer. Direct dark I,V measurements reveal that the dominant recombination mechanism is a tunnelling assisted process. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Performance analysis of a -Si:H p,i,n solar cells with and without a buffer layer at the p/i interface

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2004
G. Munyeme
Abstract Light soaking experiments have been conducted on a-Si:H p-i-n solar cells with a silicon carbide buffer layer at the p/i interface. The rate of light induced degradation in the performance of these solar cells is higher in the initial stages of light soaking and assumes the same levels as the cells without a buffer layer with prolonged light soaking. Computer modelling has revealed that a graded band gap buffer layer at the p/i interface containing a slightly acceptor doped defective layer next to the p-layer improves the initial performance of a-Si:H p-i-n solar cells. The modelling also reveals that the effect of the buffer layer on solar cell performance depends critically on the configuration and composition of the buffer layer. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Deposition of highly efficient microcrystalline silicon solar cells under conditions of low H2 dilution: the role of the transient depletion induced incubation layer

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 4 2007
M. N. van den Donker
Abstract This paper addresses the plasma deposition of highly efficient microcrystalline silicon (,c-Si:H) p-i-n solar cells under conditions of high SiH4 utilization and low H2 dilution. It was established that the transient depletion of the initially present SiH4 source gas induces the formation of an amorphous incubation layer that prevents successful crystallite nucleation in the i-layer and leads to poor solar cell performance. The effect of this transient depletion induced incubation layer on solar cells was made visible through dedicated solar cell deposition series and selected area electron diffraction measurements. Applying a gas flow procedure at plasma ignition it was succeeded to prepare state-of-the-art ,c-Si:H material and solar cells under low hydrogen dilution conditions, highlighted by ,c-Si:H solar cells of up to 9·5% efficiency prepared using an undiluted source gas flow consisting solely of SiH4. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Spatially resolved evaluation of power losses in industrial solar cells by illuminated lock-in thermography

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2004
Joerg Isenberg
Abstract The principles of a recently introduced measurement technique for power losses in solar cells, illuminated lock-in thermography (ILT), are reviewed. The main advantage of ILT over dark lock-in Thermography (DLT) is measurement under realistic operational conditions of solar cells. The main focus of this paper is to demonstrate the wide range of applications of ILT in identifying the causes of power losses in solar cells. For this purpose different evaluation methods are presented. A method for the evaluation of improvement potentials within a given cell technology is demonstrated. It is shown that different types of series resistance may be localized. Small areas of recombination losses (e.g., grain boundaries) can routinely be detected, which is not possible in dark lock-in thermography. Good correspondence with light-beam-induced current images is found. A realistic evaluation of the impact of recombination losses on solar cell performance is demonstrated on two examples. Finally, process- or treatment-induced recombination losses are investigated. In summary ILT is shown to be an extremely powerful tool in localizing, identifying and quantifying power losses of solar cells under realistic illumination conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source]