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Intrinsic microcrystalline silicon: a new material, for photovoltaics
07 Alternative energy sources (solar energy) Flat-bed sunlight collector/solar reactor for solar-photoand solarthermochemical syntheses is described. A method is also provided for performing such syntheses without a sunlight focusing device.
W/W392
Fourier analysis of meteorological data for Seeb
Dorvlo, A. S. S. Energy Corners. Manage., 2000, 41, (l2), 1283-1291. Harmonic analysis methods are used to obtain typical annual time dependent functions for the solar radiation and temperature data for Seeb, Sultanate of Oman. The first two harmonics adequately model the solar radiation and temperature data.
00100393 Hybrid organic-inorganic solar cells: case of the all thin film PMeT(Y)/CdS(X) junctions Neuven. H. Solar Enerm Mnrerials & Solar Cells. 2000. 63. (1). 23-35. Hyb;id organic-inorga& all thin film photovoltaic junctions PMeT(Y)/ CdS(X) were investigated, where PMeT(Y) is the conducting polymer poly(3-methylthiophene) doped with various anions Y = CFsSOs-, Clod-, BFd-, PFs-, and CdS(X) cadmium sulfide doped with various elements X = Cu, Ni, Al, As and Sb. CdS(X) films were spray deposited on conducting and transparent indium-tin oxide (ITO) glass, and PMeT(Y) films were electrodeposited onto the CdS(X) film to form the junction. The electrochemical investigation of the mechanism of electrodeposition and growth of the PMeT(Y) films by means of chronoamperometry and of the charge transfer behaviour of the PMeT(Y)/CdS(X)junctions by means of cyclic voltammetry revealed a strong effect of the nature of Y and X. The same strong effect of Y was also found with PMeT(Y)/ITO junctions, and may have some generalitv. . , of contact between the oreanic v , It was shown that the best aualitv and inorganic phases, from an electrochemical viewpoint and in solution, was obtained with the PMeT(PF6-)/CdS(Sb) junction, pointing towards a similarly better photovoitaic performance in solid state. This was indeed the case and it was discovered that higher shortcircuit current, open-circuit photovoltage and energy conversion efficiency, approaching 4%, could be obtained with this junction.
W/O0394 Improvement of the photovoltaic properties of polythiophene-based cells Sicot, L. Sol. Energy Mar. & Sol. Cells, 2000, 63, (l), 49-60. The photovoltaic properties of organic cells based on a polythiophene film have been studied. An external power efficiency of 10m4% has been obtained in the pristine polymer diode. In order to improve this result, three complementary routes have been investigated. Optical sensitization of the polythiophene with a dye of the indane group leads to a 75% increase in power efficiency. A hybrid molecular/polymeric pn type junction instead of the original Schottky type provides a 0.15% efficiency. Molecular rectification in oriented polymers incorporating diodelike chromophores increases the PV efficiency by a factor of 40.
In the uresent work, mean hourlv values of the luminous efficacv of direct solar radiation for clear skies in Madrid using solar elevation as the only independent variable have been modelled. Models of the polynomial type, similar to those given by different authors and a model for the direct luminous efficacv mathematicallv coherent with the corresponding models of direct iluminance and* irradiance, are developed. This last luminous efficacy model can be obtained from the corresponding illuminance and irradiance models in an apparently new approach to the subject, and shows a statistical performance as good as the polynomial models. This paper shows how arbitrary polynomial luminous efficacy models can be and tests the dependence of coefficients in these models on local climatic conditions.
00100396 Luminous efficacy of global solar radiation for clear skies Robledo, L. and Soler, A. Energy Comers. Manage., 2000, 41, (15) 1769-1779. The luminous efficacy of global solar radiation for clear skies has been modelled using solar elevation as the only independent parameter. In the present work, two types of models are developed. On the one hand, nolvnomial models similar to those uresented bv other authors are produced and on the other, a non-polynomial model for the luminous efficacy of global solar radiation is reported, as obtained from the ratio between the corresponding illuminance and irradiance models. This latter model offers an accuracy to predict global illuminance similar to that obtained with the polynomial models. However, the model for the global efficacy obtained from illuminance and irradiance models has, among others, the advantage of its mathematical coherence and its formulation uses a more definite function than the polynomial models.
Mantle heat exchangers for horizontal tank 00100399 thermosyphon solar water heaters Morrison, G. L. t-1 al. Solar Energy, 1999, 67, (l-3), 53-64. This paper describes the characteristics of horizontal mantle heat exchangers for application in thermosyphon solar water heaters. A new correlation for heat transfer in horizontal mantle heat exchangers with bottom entry and exit ports was used to predict the overall heat transfer and stratification conditions in horizontal tanks with mantle heat exchangers. The model of a mantle heat exchanger tank was combined with the thermosyphon solar collector loop model in TRNSYS to develop a model of a thermosyphon solar water heater with collector loop heat exchanger. Predictions of stratification conditions in a horizontal mantle tank are compared with transient charging tests in a laboratory test rig. Predictions of daily energy gain in solar preheaters and in systems with in-tank auxiliary boosters are compared with extensive outdoor measurements and the model is found to give reliable results for both daily and long-term performance analysis.
Microdoping compensation of microcrystalline silicon obtained by hot-wire chemical vapour deposition 00100400
00100395 intrinsic microcrystalline silicon: a new material, for photovoltaics Vetterl, 0. ef al. Sol. Energy Ma/. & Sol. Cells, 2000, 62, (l-2), 97-108. Microcrystalline silicon (pc-Si:H) prepared by plasma-enhanced chemical vaoour deuosition IPECVD) has been investigated as material for Hbsorber’layers in solar cells. The deposition pr&ess has been adjusted to achieve high deposition rates and optimized solar cell performance. In particular,-already moderate variations of the crystalline versus amorphous volume fractions were found to effect the electronic material - and solar cell properties. Such variation is readily achieved by changing the process gas mixture of silicon to hydrogen. Best cell performance was found for material near the transition to the amorphous growth regime. With this optimized material efficiencies of 7.5% for a 2 pm thick @ji:H single solar cell and 12% for an a-Si:H/ +-Si:H stacked solar cell have been achieved.
Investigation of photoelectrochemical characteristics of n-tvoe Cu, 0 films
W/W396
Fernando, C. A. N. Wetthasinghe, S. K. Sol. Energy Mar. & Sol. Cells, 2000, 63, (3) 299-308. n-CuzO photoelectrodes are obtained by immersing a copper plate in a CUSO~(~O-~ M) and HCI (10e3 M) solutions. Samnles are characterized w&h XRD and SEM measurements. It is found ihat Cu*+ ions and the copper substrate are essential to obtain n-type photoresponses from CuzO. Photocurrent action spectra are investigated with various CuaO amounts formed on the copper substrate, made from two different methods. Photoluminescence (PL) measurements of the samples prepared by the two methods are examined. Time development of the photocurrent is investigated in KI(lO-* M) + Iz (1O-4 M) and trisodium citrate solutions.
Luminous efficacy of direct solar radiation for
W/W397
clear skies Robledo,
L. Soler, A. Energy, 2000, 25, (8) 689-701.
Voz, C. et al. Sol. Energy Mar. & Sol. Cells, 2000, 63, (3) 237-246. Undoped hydrogenated microcrystalline silicon was obtained by hotwire chemical vapour deposition at different silane-to-hydrogen ratios and low temperature (~300°C). As well as technological aspects of the deposition process, structural, optical and electrical characterisations of the samples that were used as the active layer for preliminary p-i-n solar cells are reported in this paper. Raman spectroscopy indicates that changing the hydrogen dilution can vary the crystalline fraction. From electrical measurements an unwanted n-type character is deduced for this undoned material. This effect could be due to a contaminant, probably oxygen, which is also observed in capacitancevoltage measurements on Schottky structures. The negative effect of contaminants on the device was dramatic and a compensated p-i-n structure was also deposited to enhance the cell performance.
Modeling solar energy input in greenhouses 00100401 Pieters, J. G. and Deltour, J. M. Solar Energy, 1999, 67, (l-3), 119-130. A semi one-dimensional climate model was used to investigate the relative importance of the constructional parameters that influence the solar energy collecting efficiency of greenhouses under Western European conditions. Parameters investigated were the transmittance of the greenhouse frame, the radiometric properties of the greenhouse cladding and the floor, as well as the type of condensation (as a film or as drops). Their effect on the auxiliary heating requirements and the several solar energy fluxes in the greenhouse were simulated for a yearround tomato crop. The results pointed out that greenhouses catch about two thirds of the solar radiation available. This rather poor efficiency is due to the fact that greenhouses are fixed constructions, so their efficiency highly depends on their position and geometry, which are mainly determined by horticultural constraints. Most of the solar energy entering the greenhouse was found to be absorbed by the vegetation. Auxiliary heating requirements were hardly influenced by changes of the frame or cladding transmittances, although the transmittance reduction caused by condensation as hemispherical drops caused a 2.8% increase of the energy demand. The floor Fuel and Energy Abstracts
January 2001 41
W/W392
Fourier analysis of meteorological data for Seeb
Dorvlo, A. S. S. Energy Corners. Manage., 2000, 41, (l2), 1283-1291. Harmonic analysis methods are used to obtain typical annual time dependent functions for the solar radiation and temperature data for Seeb, Sultanate of Oman. The first two harmonics adequately model the solar radiation and temperature data.
00100393 Hybrid organic-inorganic solar cells: case of the all thin film PMeT(Y)/CdS(X) junctions Neuven. H. Solar Enerm Mnrerials & Solar Cells. 2000. 63. (1). 23-35. Hyb;id organic-inorga& all thin film photovoltaic junctions PMeT(Y)/ CdS(X) were investigated, where PMeT(Y) is the conducting polymer poly(3-methylthiophene) doped with various anions Y = CFsSOs-, Clod-, BFd-, PFs-, and CdS(X) cadmium sulfide doped with various elements X = Cu, Ni, Al, As and Sb. CdS(X) films were spray deposited on conducting and transparent indium-tin oxide (ITO) glass, and PMeT(Y) films were electrodeposited onto the CdS(X) film to form the junction. The electrochemical investigation of the mechanism of electrodeposition and growth of the PMeT(Y) films by means of chronoamperometry and of the charge transfer behaviour of the PMeT(Y)/CdS(X)junctions by means of cyclic voltammetry revealed a strong effect of the nature of Y and X. The same strong effect of Y was also found with PMeT(Y)/ITO junctions, and may have some generalitv. . , of contact between the oreanic v , It was shown that the best aualitv and inorganic phases, from an electrochemical viewpoint and in solution, was obtained with the PMeT(PF6-)/CdS(Sb) junction, pointing towards a similarly better photovoitaic performance in solid state. This was indeed the case and it was discovered that higher shortcircuit current, open-circuit photovoltage and energy conversion efficiency, approaching 4%, could be obtained with this junction.
W/O0394 Improvement of the photovoltaic properties of polythiophene-based cells Sicot, L. Sol. Energy Mar. & Sol. Cells, 2000, 63, (l), 49-60. The photovoltaic properties of organic cells based on a polythiophene film have been studied. An external power efficiency of 10m4% has been obtained in the pristine polymer diode. In order to improve this result, three complementary routes have been investigated. Optical sensitization of the polythiophene with a dye of the indane group leads to a 75% increase in power efficiency. A hybrid molecular/polymeric pn type junction instead of the original Schottky type provides a 0.15% efficiency. Molecular rectification in oriented polymers incorporating diodelike chromophores increases the PV efficiency by a factor of 40.
In the uresent work, mean hourlv values of the luminous efficacv of direct solar radiation for clear skies in Madrid using solar elevation as the only independent variable have been modelled. Models of the polynomial type, similar to those given by different authors and a model for the direct luminous efficacv mathematicallv coherent with the corresponding models of direct iluminance and* irradiance, are developed. This last luminous efficacy model can be obtained from the corresponding illuminance and irradiance models in an apparently new approach to the subject, and shows a statistical performance as good as the polynomial models. This paper shows how arbitrary polynomial luminous efficacy models can be and tests the dependence of coefficients in these models on local climatic conditions.
00100396 Luminous efficacy of global solar radiation for clear skies Robledo, L. and Soler, A. Energy Comers. Manage., 2000, 41, (15) 1769-1779. The luminous efficacy of global solar radiation for clear skies has been modelled using solar elevation as the only independent parameter. In the present work, two types of models are developed. On the one hand, nolvnomial models similar to those uresented bv other authors are produced and on the other, a non-polynomial model for the luminous efficacy of global solar radiation is reported, as obtained from the ratio between the corresponding illuminance and irradiance models. This latter model offers an accuracy to predict global illuminance similar to that obtained with the polynomial models. However, the model for the global efficacy obtained from illuminance and irradiance models has, among others, the advantage of its mathematical coherence and its formulation uses a more definite function than the polynomial models.
Mantle heat exchangers for horizontal tank 00100399 thermosyphon solar water heaters Morrison, G. L. t-1 al. Solar Energy, 1999, 67, (l-3), 53-64. This paper describes the characteristics of horizontal mantle heat exchangers for application in thermosyphon solar water heaters. A new correlation for heat transfer in horizontal mantle heat exchangers with bottom entry and exit ports was used to predict the overall heat transfer and stratification conditions in horizontal tanks with mantle heat exchangers. The model of a mantle heat exchanger tank was combined with the thermosyphon solar collector loop model in TRNSYS to develop a model of a thermosyphon solar water heater with collector loop heat exchanger. Predictions of stratification conditions in a horizontal mantle tank are compared with transient charging tests in a laboratory test rig. Predictions of daily energy gain in solar preheaters and in systems with in-tank auxiliary boosters are compared with extensive outdoor measurements and the model is found to give reliable results for both daily and long-term performance analysis.
Microdoping compensation of microcrystalline silicon obtained by hot-wire chemical vapour deposition 00100400
00100395 intrinsic microcrystalline silicon: a new material, for photovoltaics Vetterl, 0. ef al. Sol. Energy Ma/. & Sol. Cells, 2000, 62, (l-2), 97-108. Microcrystalline silicon (pc-Si:H) prepared by plasma-enhanced chemical vaoour deuosition IPECVD) has been investigated as material for Hbsorber’layers in solar cells. The deposition pr&ess has been adjusted to achieve high deposition rates and optimized solar cell performance. In particular,-already moderate variations of the crystalline versus amorphous volume fractions were found to effect the electronic material - and solar cell properties. Such variation is readily achieved by changing the process gas mixture of silicon to hydrogen. Best cell performance was found for material near the transition to the amorphous growth regime. With this optimized material efficiencies of 7.5% for a 2 pm thick @ji:H single solar cell and 12% for an a-Si:H/ +-Si:H stacked solar cell have been achieved.
Investigation of photoelectrochemical characteristics of n-tvoe Cu, 0 films
W/W396
Fernando, C. A. N. Wetthasinghe, S. K. Sol. Energy Mar. & Sol. Cells, 2000, 63, (3) 299-308. n-CuzO photoelectrodes are obtained by immersing a copper plate in a CUSO~(~O-~ M) and HCI (10e3 M) solutions. Samnles are characterized w&h XRD and SEM measurements. It is found ihat Cu*+ ions and the copper substrate are essential to obtain n-type photoresponses from CuzO. Photocurrent action spectra are investigated with various CuaO amounts formed on the copper substrate, made from two different methods. Photoluminescence (PL) measurements of the samples prepared by the two methods are examined. Time development of the photocurrent is investigated in KI(lO-* M) + Iz (1O-4 M) and trisodium citrate solutions.
Luminous efficacy of direct solar radiation for
W/W397
clear skies Robledo,
L. Soler, A. Energy, 2000, 25, (8) 689-701.
Voz, C. et al. Sol. Energy Mar. & Sol. Cells, 2000, 63, (3) 237-246. Undoped hydrogenated microcrystalline silicon was obtained by hotwire chemical vapour deposition at different silane-to-hydrogen ratios and low temperature (~300°C). As well as technological aspects of the deposition process, structural, optical and electrical characterisations of the samples that were used as the active layer for preliminary p-i-n solar cells are reported in this paper. Raman spectroscopy indicates that changing the hydrogen dilution can vary the crystalline fraction. From electrical measurements an unwanted n-type character is deduced for this undoned material. This effect could be due to a contaminant, probably oxygen, which is also observed in capacitancevoltage measurements on Schottky structures. The negative effect of contaminants on the device was dramatic and a compensated p-i-n structure was also deposited to enhance the cell performance.
Modeling solar energy input in greenhouses 00100401 Pieters, J. G. and Deltour, J. M. Solar Energy, 1999, 67, (l-3), 119-130. A semi one-dimensional climate model was used to investigate the relative importance of the constructional parameters that influence the solar energy collecting efficiency of greenhouses under Western European conditions. Parameters investigated were the transmittance of the greenhouse frame, the radiometric properties of the greenhouse cladding and the floor, as well as the type of condensation (as a film or as drops). Their effect on the auxiliary heating requirements and the several solar energy fluxes in the greenhouse were simulated for a yearround tomato crop. The results pointed out that greenhouses catch about two thirds of the solar radiation available. This rather poor efficiency is due to the fact that greenhouses are fixed constructions, so their efficiency highly depends on their position and geometry, which are mainly determined by horticultural constraints. Most of the solar energy entering the greenhouse was found to be absorbed by the vegetation. Auxiliary heating requirements were hardly influenced by changes of the frame or cladding transmittances, although the transmittance reduction caused by condensation as hemispherical drops caused a 2.8% increase of the energy demand. The floor Fuel and Energy Abstracts
January 2001 41